bandersnatch \BANDR-snatch\ (noun)
1. A fleet, furious, fabulous creature, of dangerous propensities, immune to bribery and too fast to flee from; later, used vaguely to suggest any creature with such qualities
In a letter from May 15, 1966, C.S. Lewis wrote "No one ever influenced Tolkien--you might as well try to influence a bandersnatch."