Paul D'Amour (born May 12, 1967 in Spokane, Washington) was the original bassist for Tool. His bass sound was ultimately characterized by the aggressive picked tone he developed with his Rickenbacker 4001CS that can famously be heard on Tool's first LP, Undertow.

Originally a guitar player, D'Amour became Tool's bassist after being introduced to the band by guitarist Adam Jones. Like Jones, D'Amour was in Los Angeles because of his wish to enter the film industry. He hadn't played music for a while and was thinking about giving it up.

In 1995 D'Amour left Tool because of a desire to do something more experimental. After his departure from the band, he formed the critically acclaimed psychedelic pop band Lusk with Brad Laner, Chris Pitman (now of Guns N' Roses), and ex-Failure member Greg Edwards (now of Autolux). In 1997 they released their only album to date, titled Free Mars.

Prior to his departure from Tool, D'Amour also played guitar in a side-project called Replicants, a cover band that included Ken Andrews and Greg Edwards from Failure, as well as Chris Pitman. They released one self-titled album in 1995, with a guest appearance from former Tool band-mate, Maynard James Keenan.

As of early 2005, D'Amour has been writing and performing under the name Feersum Ennjin, which owes its phonetically spelled name to the science fiction novel Feersum Endjinn by Iain Banks - an author whose novel The Wasp Factory was conceptual inspiration for Lusk as well. The project has one self-titled EP released on Silent Uproar Records.