(written from a Production point of view)
Monster is an orange tabby cat who portrayed Spot on Star Trek: The Next Generation beginning with the sixth season. While Monster was the "more spunky" cat, Brandy, Bud and Tyler are the other cats who played Spot. Monster can also be seen in early scenes of Star Trek Generations when he jumped on Data's table.
Monster was 'interviewed' in Star Trek Monthly issue 14. He 'noted' that the change in Spot's appearance was due to "prosthetic make-up". Monster was trained by Rob Bloch and Karen Thomas-Kolakowski of Critters of the Cinema.