Choo-Choo, nicknamed Chooch, is enthusiastic and devoted to TC even when he’s clueless as to what he’s doing. He lives at the fire house as the fire house cat as seen in one episode "Hawaii Here We Come". He had a couple of love crushes "Choo-Choo's Romance" and "Choo-Choo Goes Gaga-Gaga", however unlike Top Cat or Fancy-Fancy, Choo-Choo has no courage talking to girls. When he talks, his voice sounds like Woody Allen. He is voiced by Marvin Kaplan, Tom Kenny, and Jason Harris in the English versions and Jorge Arvizu and Gabriel Ortiz in the Latin American Spanish versions.
Choo-Choo is a slender pink cat with a peach muzzle, black eyes that resemble the eyes of a Siamese cat, a long, black-tipped tail, pointy ears with invisible eardrums, a black nose, and 4 whiskers - 2 on each side. He wears a white turtleneck shirt with long sleeves.