Sidney, better known as Sid, is the deuteragonist of the Ice Age franchise.
He is a ground sloth. He is Manny and Diego's best friend and one of Peaches' adoptive uncles. He becomes Brooke's mate in Ice Age: Collision Course.
Sid was first seen fast asleep on his home tree and wakes up, only to realize that his family left without him to migrate, so he decided to travel alone without them in annoyance at being left behind. Unfortunately, he steps in Glyptodon dung and wipes his filthy feet on the last meal belonging to two brontotheres named Carl and Frank, ruining it. To top it all off, he eats the best part of their salad: A dandelion.
This last act wanted Carl and Frank to kill him, so they chased Sid to his death, but this life was saved by a woolly mammoth named Manfred, because Manfred doesn't want other animals getting killed. Since Manfred saved Sid's life, Sid decided to stick with him to keep safe.
Manfred and Sid discovered a human infant when a saber-toothed tiger named Diego realizes that his prey has been adopted by two misfits and decided to join the gang to take the baby back just to get his paws on it.
Sid proved to be capable of creating fire, but it wasn't until 3/4 of the first movie when he created fire by accident while scribbling chalk on the cave wall. He then referred himself as Lord of the Flame.
Later, Sid held Roshan while Manny pinned Diego against a wall with his tusk. Sid never spoke in this scene but it seemed he showed fear for Manny threatened to kill Diego (possibly, by stabbing him in the throat with his tusk's point because it said in the Novel: "Manfred shifted a tusk so that it's razor-sharp point was pressed against Diego's throat like a knife.").
In the second movie, Sid tried to run a children's Water Camp, but failed due to his lack of role modeling towards younger children. He was teased and ridiculed by Manny and Diego about not qualified to run a camp or look after kids, (despite his experience with Roshan, from the first movie) Sid reminded them, that if it weren't for him, the 'herd' as they are now, wouldn't be here, if it weren't for him, Which is true, from that moment on Sid tries to look or gain respect from his two friends, later his tried to go down a very big death-defying waterfall.
But Manny and Diego stopped him just in time, to prevent him from making a very big mistake. It was also because of this, that they found out the Fast Tony was right and that the ice was truly melting. As the group traveled towards the end of the valley, Sid began to annoy Manny with various songs, about going extinct.
When Manny was feeling depressed about been that last one, Sid tries (not very hard) to cheer him up, saying that he has him and Diego. After Manny was very sad to find out that an ominous noise he though sounded like a mammoth, he set out alone to leave Sid and Diego to head off. It was then that Sid and Diego, met Crash and Eddie, who wasted no time in mocking and making fun out of them, though tunnel holes and spit balling target practice.
After Sid and Diego were defeated they chased them all the way towards another mammoth called Ellie, who thinks she's a possum. It was that Sid suggested asking Ellie and the Possum brothers to come along with them to escape the flood, despite everyone's furious reactions towards each other. But Sid tells Manny that he may the only Mammoth left on earth along with Ellie, and that this may be a chance to get them 'together'.
Sid's idea would proved to be fatal towards the end of the movie. As the others continued he journey, he noticed Diego's fear of the water and tries to talk him into out coming his fear, by giving him a sinking rock demonstration lesson and how to kick and claw though water, in the middle of the movie, which would proved to be useful near the end However he was ignored by Diego who would try to prevent himself from listening to this advice.
After a near death experience along with the others, he helped his friends, reasoned with Manny and Ellie to apologize to each other. Later that night, he was kidnapped by a tribe of colorful mini-sloths as they somehow discovered that he could create fire with flint and therefore hailed him as the legendary Fire King to bring peace and harmony to the valley, by giving Sid a respected outlook of waiting for commands made by him, much to his delight, however this was short lived as they revealed to only to try and sacrifice him in order to stop the flood, but failed due to a fortunate mishap and a destruction chaos throughout the mini sloths valley, where Sid finally escaped from them by rolling in a his statue's eye.
In the morning Sid tries to tell them of his experience, but no one believed him. As, they journeyed though the valley of the vultures, Sid and the others were almost targeted as food before escaping. Later Sid sung it, much to the annoyance of the others, which he finds is catchy to his liking.
After Manny and Ellie have another argument and split up, Sid and Diego tries to talk Manny out from killing himself though the geysers. But, after Manny realizes how his has been believing throughout the journey, he realized that they needed to find Ellie and the others. When the water arises and the possums were stranded by rising water, Sid offers to save them, but this backfires when he hit head first in a chunk of ice, Leaving the possums to rescue him instead.
Finally, after much effort, Diego finally takes Sid's advice of the water and saves Sid and the possums. When Sid congratulated him, he mentions that he left the part where Tigers can't swim, much to Diego's surprise. Sid and the others become spectators to Manny's fight with the under water predators.
Sid later help Ellie get on shore along with the Possums. Sid's joy turns to despair as the water rises up, but a fatal disaster helped by Scrat unnoticed withdrew the water from the glaciers, restoring the valley back to normal.
Sid considers running a swim school for kids, just as he sees the mini sloths again who thank him for ending the flood and ask him to join them, Sid was about to consider, until Diego stop him, telling the mini sloths, that Sid has other priorities such as staying with his herd, as he made the herd into a bigger herd and that they would be nothing without him, much to Sid's joy and happiness, that he hugs Diego in gratitude, despite Diego's reluctantly, when the others finds the mini sloths, they turn towards Sid and Diego who said in a low embarrassed voice, "Don't ask."
However, despite how things turned out the group decided to split again, leaving a tearful possums to say good-bye to Sid and Diego, before they set off. Sid convinces Manny to go and be with Ellie along with Diego, saying that they'll always be here for him. Sid along with Diego then thought, since Manny had Ellie, he didn't need them around anymore and set off by themselves, however Manny quickly picks up Sid and tells Diego that now they are one 'herd', letting Sid know that at last they are one big happy family at last.
By the third film, Ellie and Manny are expecting their first child, which makes emotional changes on the other members of the pack, Especially to Manny, Crash, Ellie, Eddie and Sid who are excited at the prospect of a new member to their herd and after Manny shows Ellie around the new playground that he had built for their child.
Sid feels disappointed when he finds that he isn't up on Manny's new mobile, despite Crash and Eddie's attempts by presenting a bug mobile, cheering Sid up a little bit and Diego thinks he has become to grow too soft and decides to leave the herd.
After telling Sid that things have change and that Manny has other priorities now, and that it has been fun while it lasted, making Sid a bit uneasy, while he ask Diego if it's just two of them, or perhaps the possums. Diego leaves him, little realizing the effects his words has left.
This has left Sid feeling alone, fearing for an isolated and uncertain future without his friends' support besides him and focus on the baby instead. His weak efforts to win new friends, doesn't go well and ends up falling in an underground cavern where he finds three dinosaur eggs, not knowing what these are inside, tells them he knows what it's like to feel abandoned, he realizes that this to still be part of family, by starting a new one.
Manny and Ellie find Sid with the dinosaur eggs and Manny immediately tells Sid to take them back, because they were not his eggs, and that he was not meant to be a parent, much to Sid's chagrin. Manny makes it worse by saying "he will meet a girl with low standards," greatly offending Sid. Ellie became a little worried about Sid after he huffs off, but Manny didn't take him seriously (Just like in the 2nd film).
Sid is determined to prove Manny wrong, by saying he can be a good parent and raise them himself. Despite his doubts, he is encouraged by the sun above, when it's shine upon the eggs, comforting Sid that all will be alright in time.
When Sid wakes up the next morning, he finds to his surprise that three new dinosaurs have been hatch and born out of the eggs overnight. Sid, happy at the prospect of been a 'Mother (Although he's a father) rises the kids, blissfully for a few hours.
Later, when the dinosaurs wanted to play in Manny's new playpen, Sid was reluctant, because Manny said it's just for kids, but realizes that the babies were kids, and lets them and the other animals play and unintentionally cause chaos, destroying everything in sight and eating the other animals, poor Sid tries to stop them, but they are too rambunctious to listen or obey. When Yoko wrecks Manny's mobile, Manny is furious with Sid and demands to take them back to where he found them, but Sid has already grown fond of his kids and refuses to because he's already a parent to them. When Momma dinosaur came into the animals homeland looking for her babies, Manny tries to reason with Sid to give them back to her, but because Sid has grown fond of his 'new' children, he refuses to let that happen. This has lead Sid to his abduction, as Momma dinosaur takes him and her children to the underground dinosaur world.
While the other animals set off to rescue their friend, Sid almost gets eaten by Momma dinosaur and tries to calm her down, by offering to take turns to look after the kids, but she is too furious to listen, the dino babies defend Sid, because they have grown to love him. Momma still furious let Sid live for now.
As, he waits to be rescued, Sid tries to get them to eat vegetables, but doesn't know that T-Rexes do not eat vegetarian food and he and Momma end up in a debate battle to say who's right about raising them. Momma wins the fight, but hears the sound of Rudy, Sid who doesn't know about Rudy, asks what she is afraid of, because she's the biggest thing on earth.
When Momma takes her babies up to a cave to sleep, minus Sid, It then that Sid admits that he misses his friends, but sadly says that they probably aren't missing him. Momma hearing this, Sid as she tucks him with her tail and lets him sleep with her babies. Sid thanks her.
The next Morning, Sid and his children play, but he cannot keep up with them, it was then that he meet Rudy, who chased him towards lava falls as he corners and traps Sid in some small floating pieces of rock as Sid floats on the boiling hot lava towards a dreadful fall over the lava waterfall.
Buck, Crash and Eddie went ahead of the herd to rescue Sid, when Ellie was in labor. They see Sid near the lava falls and had to face great obstacles in order to get to him. At the same time, Sid tries his best to hang on and escape by himself, but with little luck. Just when Sid think this is it, he prepares nobly to face his death.
But, at the last second, Sid was rescued in the nick of time as Crash, Eddie and Buck tell him that they are here, as they set off back towards the others. Sid sees Peaches for the first time and exclaims it's a boy, until Diego corrected him by saying that it is's tail, Sid then says correctly that it's a girl and goes over to say hello to Peaches, who grows an instant liking to Sid.
He respectively exclaims how she looks like her mother and Manny and Diego admit that they missed him. Sid regretfully wishes that his kids were here, that they could have friends with Peaches, as Peaches walks over to him and places a friendly trunk on his hand, marking there would be lifelong friendship.
Later Sid, helped the others help Buck as they stopped Rudy from hurting the herd, But Sid trips over the vines that secured Rudy and was about to kill Sid, when Momma saves him by headbutting Rudy sending him to his death.
Sid cheers for his children and Momma celebrated their victory, Sid then tearfully says goodbye to his former children, knowing that this world is where they truly belong. As well as Momma who kisses him. Manny admits as he comforts Sid that he was a good parent. Sid then asks Manny if he can babysit Peaches, Manny says no, then tell Sid he'll think about it. But, whispers to Diego that he never let it happen.
When they reached back up to the surface, Sid watches happily with Manny and Diego as they see Peaches having fun with Crash and Eddie in the snow. Sid says that they grow up so fast, as if yesterday his kids were born and gone the next, Diego reminds saying that they were. Sid admits this saying it was a lot of hard work and like Manny he is watchful as the future of the ice age looks bigger.
In the fourth film, Sid gets a surprise as his family who'd abandoned him years ago all breeze into the herd just long enough to dump their 80-year-old Granny for Sid to take care of and promptly leave once his back is turned.
Shortly after, the continental divides separated Manny Sid, Diego from Ellie and Peaches. After barley escaping a storm, Sid's irritable grandmother Granny is revealed to have slept though the whole thing. Later, the herd encountered a group of animals that declared themselves pirates atop an iceberg ship: the pirate captain, an ape named Gutt who offered Manny and the herd to join the crew. Manny refused stating no one will stop me from getting back to his family. Gutt's calm demeanor quickly disappeared into a look of pure evil, stating to Manny that his family "will be the death of you." . The ape then tried to make them walk the plank, starting with Sid and Granny.
Gutt then ordered his first mate Shira to prepare the plank for the castaways to be jettisoned off of, forcing them all to walk the plank off the ship and into the ocean, where angry narwhals awaited them, ordering Sid to go first. At that moment, Gutt halted the walk, to Sid's temporary relief, so that Granny, the older sloth, would go first, offering his hand in an oily manner to help the old sloth move. As the two were about to walk the plank, Manny, along with Diego, worked out how to escape their bonds and toppled the ship to the side, preventing the sloths from falling into the waters. As everyone escaped (with Shira who was abandoned by Gutt) they reach Switchback cove. Manny gets an idea to steal Gutt's replacement ship but realizes the Hyraxes cannot understand him. Sid uses some gibberish to get the resident Hyraxes to understand him and they agree to help.
Manny instructs Sid and Granny to unwind the vines and don't let go until the gang is on board. However, Sid fails to carry out his part of the plan because he finds a lotus berry and swallows it and it paralyzes him.
Later after the herd succeeds in stealing Gutt's ship, Sid recovers from the berry chatting non stop. He and Manny then tease Diego realizing that he's falling in love with Shira. Diego denies it.
The herd finally arrives at the continent, only to discover that Gutt and his crew had beaten them there and holding Ellie and Peaches hostage. Just as everything seems hopeless, Louis, Peaches' friend stands up to the big ape, demanding that he release Peaches. Gutt, amused at Louis' gumption, accepted the challenge laughingly, ordering Gupta to let the molehog have his blade. Gutt then openly laughed at Louis, who could barely pull the blade out of the ice where it stood, but stopped his laughter once he saw that Louis pulled the blade out. Calling for Louis to fight, Gutt stood by, watching as Louis flung the blade into the air, where it fell into the ice: Louis instead burrowed through the ice towards Gutt, where he leaped out at once and smashed a heavy piece of ice on Gutt's foot, the pain making him release Peaches, and the battle is on.
Sid and Granny are chased to the deck's edge and Granny calls out for "Precious" and to Sid's surprise, Precious actually exists--she's a giant Whale. Granny willingly enters the whale's mouth while Sid reluctantly follows. Gutt stood ready to attack the herd when Precious, arose from the waters, and Sid positioning himself on her blowhole, directs the sprays of water to blast away Gutt's crew, one by one.
After Manny defeats Gutt, he tells Sid that he is no screw up but a hero. The entire herd then moves to Switchback cove and Sid gleefully hugs his hyrax buddies. Sid then presents Granny with a pair of shark dentures.
Sid and his girlfriend, Francine, went on a 14-minute date, and later, Sid got a ring and put it in a clam shell. Planning to propose to her, he practiced with himself, looking into ice. He kissed the ice, making his lips stuck to it, but he was able to get free from it and propose to Francine. In the middle of it, Francine told him that she was going to stop right there and told him she was breaking up with him. Sid was upset and wiped his tears away with poison ivy. Sid found his friends Manny and Diego. Manny got him cleaned up and Sid went to Manny and Ellie's anniversary and got a fruity drink. Sid noticed a fiery ball in the sky and showed it to Diego, who told Manny. It was meteor shower. They went into an Ice Cave and stayed until they thought it was safe.
After this, they found their old pal, Buck. He lead them and Sid's fur got poofy after an electrical storm came through the forest. Buck saved a pumpkin and named it Bronwyn. Buck told the herd to rest for the night. In the morning, Sid discovered Granny was missing. This made Sid very upset. Sid told the herd he could still hear her yelling. It wasn't in Sid's head, and they followed it.
They found that a prehistoric rabbit called Teddy was giving Granny massages. They were in a crystal place called Geotopia. A ground sloth called Brooke, fell in love with Sid, and called her squad of two minicorns, Bubbles and Misty. Bubbles and Misty brought Sid toward Brooke. Brooke checked Sid's jaw and face and was very impressed. Brooke told the herd she'd bring them to her master. With that said, Bubbles and Misty tapped the crystal floor with their hooves, releasing the crystal hoverboard. The crystal hove boards took them to the Geotopian leader. Once they got there Shangri Llama, the llama leader, greeted the herd and taught them various yoga positions. Sid and Brooke were on a 12-minute date and Brooke proposed to Sid. Sid agreed and tried to get a crystal for her. It destroyed the entire Geotopia wall. Shangri Llama was extremely mad at Sid, for the crystals gave them the power to stay in their youth. Brooke became elderly, but Sid still loved her. The Geotopians agreed to give up their crystals to a volcano. The volcano and crystals pulled the asteroid away from them, throwing it elsewhere in space. Brooke kissed Sid to celebrate their victory.
Brooke had to stay in Geotopia, making Sid sad. Brooke told Sid she'd have Granny to keep her company. Sid was sad that both his love and grandmother were staying. Brooke gave Sid a stone-crystal with a drawing of herself on it. Sid quickly did the same with another stone, drawing himself, and giving it to Brooke. Brooke loved it.
At Peaches' wedding, with Sid being the wedding planner, Peaches was happily married to Julian. Sid looked at his stone of Brooke sadly and saw Brooke. They ran up to each other, and Brooke lifted Sid up. Brooke sang My Superstar for Sid. After the wedding, Manny states that Sid did a great job as the wedding planner and that he owes him big time. Sid then handed the mammoth a bill, which Manny deemed outrageous.
- Sid is the only character who has interacted with Scrat at least once in every film.
- In the first film, he attacks Sid when the latter tries to eat his acorn, successfully regaining it. He later meets Manny, Sid, and Diego asking him where the baby's family is and Scrat attempts to tell them about nearby saber-toothed tigers, but Diego kicks Scrat away before he could do so.
- In the second film: At the end, after Scrat created a hole in the valley and released all the melted ice, later attacks Sid for saving his life (when he had already died and gone to paradise and was about to get a giant acorn).
- In the third film, Scrat is stepped on by Manny and falls onto Sid's head while chasing his acorn. Next, he appears when Sid's "children" are batting a ball around, the ball actually being Scrat. Lastly, while Diego is sleeping, he wakes up when he gets hit with Scrat's acorn.
- In the fourth film, when Sid pries open a clam, he finds Scrat inside. Sid's Granny mistakes Scrat for a rat and continuously whacks him with her cane until he falls into the ocean.
- Originally, Sid was to have an admirer: a female sloth named Sylvia, whom he was repulsed by and kept trying to get rid of. Sylvia was eventually cut out of the film due to having no impact on the main plot, and she made Sid come off as somewhat of a jerk. The deleted Scenes with Sylvia are available on the Ice Age Super Cool Special Edition.
- In the third film he's the overall main protagonist of the story while in the fifth film he's reduced to a supporting character for unknown reasons.
- John Leguizamo tried about 30 different voices for Sid. After viewing a documentary about sloths, he learned that they store food in their mouths; this led to him wondering what he would sound like with food in his mouth. With this, along with seeing the character model, he developed the lisp and decided that it was the perfect voice for Sid.
- Ray Romano and John Leguizamo's children have voiced small cameos in almost all the sequels.