A reptile was a type of cold-blooded animal.
During the 22nd century Dalek invasion of Earth, many animals escaped from zoos during the plague. Most of them died, but reptiles such as alligators thrived in the London sewers. (TV: The Dalek Invasion of Earth)
Dodo Chaplet pointed out a chameleon to Steven Taylor while they were aboard the Ark. (TV: The Ark)
The Cynrog were reptilian humanoids who hid behind masks and worshipped the chaos god Balor. (PROSE: The Nightmare of Black Island)
The Re'nar were intelligent lizard-like reptiles from the Matrua Nebula that were at war with the Ju'wes. (COMIC: Ripper's Curse)