Born in Phoenix, AZ, and a short time later moved to Orange County, CA. By age ten, he was an avid fan of fantasy and science fiction movies. Influenced by films such as PLANET OF THE APES, KING KONG, and JASON AND THE ARGONAUTS, Gillis began making his own amateur movies, and by age thirteen had decided that creating creatures for Hollywood was to be his career. His first professional job was on Roger Corman's low budget space-epic, BATTLE BEYOND THE STARS (1980). There he worked with many other talented industry newcomers, most notably director James Cameron. The next eight years were spent first attending UCLA's film school, then working for some of the industry's top names in make-up effects, most notably Stan Winston (ALIENS, LEVIATHAN, ALIEN NATION). It was during his years with Winston that Gillis met his future business partner, Tom Woodruff, Jr. In 1988 they left Stan Winston Studio and formed Amalgamated Dynamics, Incorporated (ADI). Dedicated to the highest standards of quality in Animatronics and Special Makeup, Gillis and Woodruff have created effects in such films as TREMORS (1990) and ALIEN3 (1991), for which they were Oscar® nominees. In 1993 the duo won the Best Visual Effects Oscar for their work on DEATH BECOMES HER, although Gillis was not named in the nomination. Other career highlights include animal characters for JUMANJI, Tim Allen's fat make-ups for THE SANTA CLAUSE movies, and another Visual Effects Oscar nomination for STARSHIP TROOPERS. Gillis' special makeup effects credits include FRIDAY THE 13TH: THE FINAL CHAPTER (1984), THE GRIFTERS (1990), STAY TUNED (1992), THE X-FILES (1998), MY FAVORITE MARTIAN (1999), HOLLOW MAN, BEDAZZLED, and THE 6TH DAY (all 2000), PANIC ROOM (2002), ALPHA DOG (2006), and LONELY STREET (2007). His creature effects have also been used in COCOON (1985), INVADERS FROM MARS and ALIEN (both 1986), THE MONSTER SQUAD (1987), ALIEN NATION (1988), LEVIATHAN (1989), DEMOLITION MAN (1993), WOLF (1994), MORTAL KOMBAT (1995), MICHAEL (1996), STARSHIP TROOPERS and ALIEN: RESURRECTION (both 1997), CAST AWAY (2000), BUBBLE BOY (2001), JOHN Q (2002), SCARY MOVIE 3 and LOONEY TUNES: BACK IN ACTION (both 2003), AVP: ALIEN vs. PREDATOR (2004), ELEKTRA (2005), FAILURE TO LAUNCH (2006), and ALIENS vs. PREDATOR: REQUIEM (2007).

Nominated for Achievement in Visual Effects 1992: ALIEN3 (w. Richard Edlund, Tom Woodruff, Jr. & George Gibbs)  Nominated for Achievement in Visual Effects 1997: STARSHIP TROOPERS (w. Phil Tippett, Scott E. Anderson & John Richardson) 2 nominations