Alec Dougal Gillis is an Academy Award-winning American special effects artist and actor who served as part of the creature effects crew on the 1986 film Aliens, the 1992 film Alien3, the 1997 film Alien Resurrection, the 2004 film Alien vs. Predator, the 2007 film Aliens vs. Predator: Requiem and the 2018 film The Predator. He also appeared in a cameo as an unnamed technician in Alien vs. Predator, although he was not credited for the role.

In 1988, Gillis co-founded Amalgamated Dynamics, Inc. (ADI) with Tom Woodruff, Jr., and the company has since provided creature effects for Alien3, Alien Resurrection, Alien vs. Predator and Aliens vs. Predator: Requiem.

Gillis's work has won an Academy Award for Visual Effects (for Death Becomes Her, although he was not listed on the official nomination) and a BAFTA. For his work on Alien3, he was nominated for an Academy Award for Visual Effects, a BAFTA and a Saturn Award.