debunker

noun

1. Someone who debunks.

   “Interest Rate Observer, and a debunker of U.S. stocks since the Dow was at 2,000, has appeared on Rukeyser's TV show, where he gets bear-baited: "World's going to hell again, eh, Jim?"”

   “Still, something strange was afoot in Rendlesham, and even if the file is unlikely to satisfy either ufologists or debunkers, it suggests that the truth is still out there.”

   “Philip J. Klass belonged to the small and somewhat peculiar class of individuals known as debunkers.”