Scrat is a "saber-toothed squirrel" (a fictional species) that appears in the 2002 film Ice Age, its sequel, the 2006 film Ice Age: The Meltdown, and the 2009 film Ice Age: Dawn of the Dinosaurs. He is best known for being obsessed with acorns, constantly putting his life in danger to obtain and protect them. Scrat has also appeared two short films.
In the first, entitled Gone Nutty, he loses his meticulously-organized collection of acorns in a catastrophic chain of events. By ramming his acorn into the hole in the exact middle of the collection, he shatters the pile and, incidentally, the continent and accidentally starts continental drift. In the second, No Time for Nuts, he finds a time machine left by an unfortunate time-traveler, and visits a number of historical events.
In all Ice Age movies, as well as in the short films, Scrat is voiced by Chris Wedge. He never directly interacts with the story's main characters, except a) in the middle of the first movie where Manny asks him for directions on where the baby's family is, b) at the end of the second film, where he creates a hole in the valley and so releases all the melted ice, and c) when he attacks Sid for saving his life (when he actually died and went to heaven and was about to eat a giant acorn).