Olaf is a side character in Disney's latest smash hit, Frozen. Originally a snowman made by Elsa when she and Anna were children, he's recreated following Elsa's accidental reveal of her powers during her coronation ceremony. Anna and Kristoff come upon him while making their way to the mountain to find Elsa. Olaf quickly agrees to help them in their quest to bring back summer, not understanding that snow plus heat equals big puddle of snowman.
Olaf does whatever he can to help everyone. He's friendly, amusing and in my humble opinion, one of the best sidekicks to come out of animated films in quite some time.