Bahamut (Arabic بهموت Bahamūt) originated as an enormous whale in ancient pre-Islamic Arabian mythology. Upon Bahamut's back stands a bull with four thousand eyes, ears, noses, mouths, tongues and feet called Kujuta (also spelled "Kuyutha") (compared with the pair of Behemoth and Leviathan). Between each of these is a distance of a 500-year journey. On the back of Kujuta is a mountain of ruby. Atop this mountain is an angel who carries six hells, earth, and seven heavens on its shoulders.
Another version of the Arabic story is that Bahamut is indeed a dragon and he stands on a whale called Liwash.
In modern times, the game Dungeons & Dragons is responsible for reimagining Bahamut as the king of dragons, a benevolent Platinum Dragon; the opposite of the malevolent Tiamat, the five-headed Chromatic Queen of Dragons.
Usage
See Special:Whatlinkshere/Etymology:Bahamut for a list of articles using this term.