Lizard

Lizards were a species a reptile.

In the 1970s, Professor Tansbury's experiment resulted in the creation of a giant lizard. (TVC: The Tansbury Experiment)

On Uxarieus in 2472, IMC tried to drive off the the colonists living there by using a robot and projections to make it appear that giant lizards were attacking the colonists. (DW: Colony in Space)

The Doctor, John and Gillian visited a planet inhabited by giant lizards which briefly captured them. (TVC: Lizardworld)

The Doctor briefly turned Chris Cwej into a lizard. (NA: Sky Pirates!)