Bandersnatch
A fleet, furious, fuming, fabulous creature of dangerous propensities, immune to bribery and too fast to flee from. Later used vaguely to suggest any creature with such qualities.
The word was invented by Lewis Carroll (Charles Dodgson) and it makes its first appearance in Alice Through the Looking Glass (1871). The OED suggests the name is a portmanteau word like its stock epithet frumious.
Needless to say this beast has never been photographed.