Mr. Jolly is Leonard's pet tabby cat. He is a big, blobby, romantic cat that is afraid of the outside. When he was a kitten, he was abandoned by his father while he was still with his mother and litter. At one point while he was still a kitten, he was taken to an animal shelter and adopted by Leonard and his mother.
Mr. Jolly stays at home with Pretty Boy, Leonard's bird and they have adventures of their own while Scott and Leonard are at school. He left the house twice.
In one, Leonard brought him for pet day while Scott brought Pretty Boy
In another, he and Pretty Boy went to Leonard's school again because they thought they were each missing.
In the movie, he and Pretty Boy go on a road trip to find Spot to warn him about Dr. Ivan Krank. After getting lost in Cuba, hitching a ride with bikers, sneaking on a plane, and arriving by a viaduct they make it to Leonard and they find out has happened to Spot.
When Leonard goes to turn into a dog, Spot (as a man) shows up and they warn him about Leonard going to the lab. And they go to save him. At the lab, Jolly is turned into a butt-ugly man for a few seconds. When Krank is turned into a mouse, Jolly chases him outta the lab.
At the end, Spot (who is a dog again) has a plan on how to get home. He dresses up as Scott and Jolly and Pretty Boy are hiding under the bed.
- Jolly is similar to Garfield.
- Jolly speaks in a Shakespearean manner.
- Jolly has a lisp.
- Jolly is the last character to be originally voiced by the late David Ogden Stiers.