Tom Woodruff Jr.is an American special effects artist and actor who portrayed the Lead Alien in the 1997 film Alien Resurrection and 'Grid' in the 2004 film Alien vs. Predator.
He also portrayed the Alien in the 1992 film Alien3 and the Predalien (as well as the normal Aliens and very briefly, Wolf) in the 2007 film Aliens vs. Predator: Requiem along with cameos as a salvager in the 1986 film Aliens and an unnamed technician in Alien vs. Predator, though he was not credited for these roles.
Aside from his appearances on-screen, Woodruff has worked extensively behind the scenes on the Alien films. As part of Stan Winston's special effects team, he worked on the creature effects for Aliens; co-founded Amalgamated Dynamics with Alec Gillis and went on to provide practical effects for Alien3, Alien Resurrection, Alien vs. Predator and Aliens vs. Predator: Requiem.
Woodruff has won an Academy Award for Visual Effects for the film Death Becomes Her. For his work on Alien3, he was nominated for an Academy Award for Visual Effects, a BAFTA and a Saturn Award. He is frequently listed among the top 10 creature performers.
Information taken from http://avp.wikia.com