Tiamat is a primordial goddess of the ocean in Mesopotamian religion. The game Dungeons & Dragons has Tiamat as a chromatic dragon, the Queen of the Evil Dragons, and as such the opposing deity to Bahamut, who is a platinum dragon and the King of Benevolent Dragons.
Usage
See Special:Whatlinkshere/Etymology:Tiamat for a list of articles using this term.
This is an etymology page: a page detailing the origins of terminology used in the series in regards to real world culture and history.