Scrat is a crossover of a squirrel and a rat (hence the name Sc-rat), is small and has brownish fur. He has a pointed jaw like a rat and a body similar to a squirrel. Scrat also has small saber-teeth similar to a saber-tooth tiger and a large football shaped bushy tail about as big as his body.

Scrat is always seen chasing his acorn. Once succeeded, he usually hugs it, buries it or pretends to eat it. This doesn't last for long as he always loses it. Scrat is usually a glutton for punishment, having to risk his life to get his nut back. He was struck by lightning, chased by avalanches, got into fights with piranhas and Sid (In the first film after the dodo bird fight). Scrat is also nutty when it comes to his acorn. As mentioned by Karen Disher (voice of Scratte) in Ice Age commentary, for Scrat, his acorn always, always, always comes first.

Manfred "Manny", is a woolly mammoth, shown as one of the main protagonists in all four Ice Age films. He can be serious and emotional, but is otherwise caring and friendly. In the first film, while passing through the icy cavern, the herd discovers cave paintings of mammoths who were killed by Paleo-Indian hunters; this is an emotional moment for Manny, indicating that the pictures could be him and showing us his history or also indicating that something similar happened. At the end of the film, Manny and Sid return Roshan to the neanderthals with an injured Diego trailing behind them. He finds love with Ellie in Ice Age: The Meltdown.

In Ice Age: Dawn of the Dinosaurs, he has a daughter named Peaches. In Ice Age: Continental Drift, he gets into an arguement with his teenage daughter before being pulled away in by the drift with Diego, Sid and Granny. He and the team later encounter a group of pirates lead by Captain Gutt. When the team escaped they destroy the ship and take Shira with them. This enrages the Captain who hunt them down. Later on he is almost manipulated by sirens. He is voiced by Ray Romano.

Ellie is a female woolly mammoth. She debuted in Ice Age: The Meltdown where she met Manfred, Diego and Sid. Ellie has two "adopted" opossum brothers named Crash and Eddie. She and Manny eventually become mates and later give birth to a daughter, whom they name Peaches.

Crash and Eddie are two antagonizing twin possum brothers, who both first appeared in Ice Age: The Meltdown. As children during the Ice Age, Crash, Eddie and their mother adopted an young abandoned mammoth called Ellie, making her forget her origins and making her think she's an opossum. In the later years, they are met by Manny, Diego and Sid who were trying to escape from the flood and soon become part of the gang/family.

Diego is a smilodon (commonly known as a "saber-toothed tiger"), the most distinctive characteristics are his long canine teeth, locks of hair as sideburns and a short tail. He also has a peculiar straight line of hair in his back that is darker than the rest of his fur.

In Ice Age, Diego is first shown as being the sinister and serious type, but he softens as he travels with Manny and Sid to return a baby to his human tribe. In the second film, Diego is less hostile, showing a calm, cool-acting personality; but he hides his fear of water, which Sid finds out about. In the third film, Diego joins the herd in the underground Dinosaur World in order to rescue Sid.

Sid is portrayed as unfit and naive. However, he is also talkative, positive, caring, and loyal towards his friends.

Though childish and goofy at times, Sid shows keen insight into the lives of his friends and interests of the herd, such as seemingly being the only one aware of Diego's fear of water and Manny's growing crush on Ellie, in the second film.

Sid also suffers from a lateral lisp, which makes his "S" and "C" pronunciation rather "wet" or "spitty".Sid is usually the one getting knocked about, either by accident or on purpose.He is considered the only character with bad karma, but immediately learns his lesson soon afterwards.

Captain Gutt was a Gigantopithecus that took to being a self-styled master and captain of the high seas, taking whatever food he could find by theft and hoarding it with the help of his crew.

Shira is a female smilodon who appears in Ice Age: Continental Drift. She is introduced as one of Captain Gutt's pirates and becomes Diego's love interest afterwards. She is voiced by Jennifer Lopez.