In newer cartoons, the white fur is gone. In the 1940s and early 1950s, he had white fur between his eyes. However, over the years (since the episode Dog Trouble), he has become almost completely bipedal and has human intelligence and he is similar to his previous appearance, in 1945 shorts he had twisted whiskers and his appearance kept changing. For example, in his debut, he was quadrupedal. Tom has changed over the years upon his evolution, especially after the first episodes. The cat was known as Jasper during his debut in the short however, beginning with his next appearance in The Midnight Snack he was known as Tom or Thomas. Created by William Hanna and Joseph Barbera, he is a grey and white anthropomorphic domestic short haired mute Tuxedo cat who first appeared in the 1940 MGM animated short Puss Gets the Boot. Thomas Cat is a fictional character and one of the two titular main protagonists (the other being Jerry Mouse) in Metro-Goldwyn-Mayer's series of Tom and Jerry theatrical animated short films.

Tom was originally known as Jasper during his debut in that short, however, beginning from his next appearance in The Midnight Snack and onwards, he is known as Tom or Thomas Tom is a blue/grey anthropomorphic domestic short-haired cat who first appeared in the 1940 animated short Puss Gets the Boot. This character was created for the purpose of study, practice, animation challenges and communal content creation projects.