Dragon

Dragons were creatures from Earth myths and legends, resembling giant lizards.

The First Doctor encountered a fire-breathing dragon in the forest outside the Pied Piper's castle, but drove it off with a fire extinguisher. (TVC: Challenge of the Piper)

Senator Alcott's fear of the Chinese manifested itself as a Chinese dragon. (DW: The Mind of Evil)

Humans labelled the Draconians as Dragons, an unflattering nickname. (DW: Frontier in Space)

Dragons were one of the life-forms found on Avalon. (MA: The Sorcerer's Apprentice)

The dragon of Iceworld was a biomechanoid assigned to keep the Dragonfire away from Kane. (DW: Dragonfire)

Dragons also existed in the dreamrealm inhabited by Avalon. The Fair Folk used them to harass infantry and prevent UNIT's domination of the air through the use of fighters. The Eighth Doctor rode one deep into Fair Folk occupied territory in order to attempt to forge a ceasefire (EDA: The Shadows of Avalon)

When the Timewyrm took full possession of Chad Boyle's body, she reshaped it into the form of a small dragon. (NA: Timewyrm: Revelation)

The Bestiary of Legendary and Magical Creatures created a dragon out of human and animal body parts. (ST: Phoenix)

On one world, Enamour was produced by a mechanical dragon. (NSA: The King's Dragon)

The Eleventh Doctor, Amy Pond and Rory Williams visited a world of dragons while trying to get to Rio de Janeiro. (NSA: The Glamour Chase)

During his confrontation with Light, the Seventh Doctor mentioned dragons, among other imaginary creatures, which Light had failed to catalog. (DW: Ghost Light)