Buck is a character in the Ice Age franchise. He is a weasel that lives in an underground dinosaur world when he fell into it, many years ago. He is a major character in Ice Age: Dawn of the Dinosaurs and Ice Age: Collision Course, a minor character in Ice Age: Continental Drift, and the titular protagonist of his spin-off film The Ice Age Adventures of Buck Wild.
Buck helps the team go into the Dino World to rescue their missing friend, Sid, who was taken by Dino Mama with her children.