Snake

Snakes were a variety of reptiles of the suborder Serpentes on Earth. They were often regarded as fearful and representative of evil.

According to Greek mythology, Medusa had snakes for hair. (DW: The Mind Robber)

A type of giant snake was native to Metebelis III at some point in its history. (DW: The Green Death)

Styre's experiments on Sarah Jane Smith caused her to hallucinate a snake on her arm. (DW: The Sontaran Experiment)

The Fourth Doctor angrily referred to Calib as a "rattlesnake" for having stabbed Leela with a Janis thorn. (DW:The Face of Evil)

In the Arizona desert, the Tenth Doctor and Donna encountered an alien which had mutated into a giant rattlesnake. (DWBIT: Sting of the Serpent)

The Mara took the form of a giant snake. (DW: Kinda, Snakedance)

Giant purple Ice Snakes lived on Centuria. (DWBIT: Enemy Mine)

The Church once fought Lava Snakes. (DW: The Time of Angels)

A giant species of snake called the Oroborus was able to consume time. (K9TV: Oroborus)