Sir Leo is a famous cat whose appearance resembles Garfield's. He speaks with a British accent.

Sir Leo once stayed at Jon Arbuckle's house to relax, getting away from the constant presence of fans and paparazzi. Garfield filled in for him during this time due to their physical similarities. When Leo became too comfortable with Garfield's laid back lifestyle, Garfield gets him out by damaging Leo's reputation. The two finally go back to their regular lives.
He was an actor in movies.