(written from a Production point of view)
Jean-Luc Martin is an actor, stuntman, producer, and artistic performer who portrayed the big head sack suit guy in the Star Trek: Voyager second season episode "The Thaw". As a background actor, Martin received no credit for his appearance and was identified by the name tag of his costume, which was sold off on the It's A Wrap! sale and auction on eBay. 
Martin started his career as a performer of the Cirque du Soleil in 1986 and toured through Europe and Northern America. In the early '90s he moved to film and television work and portrayed supporting characters, including stunt work, in series such as Melrose Place, 3rd Rock from the Sun, The Pretender, Profiler, V.I.P., Rescue 77, Charmed, The Burning Zone (1996, starring James Black, Michael Harris, Jeffrey Dean Morgan, and with Alicia Coppola), Babylon 5 (1997, with Bill Mumy and Marjorie Monaghan), and Beverly Hills, 90210 (1999, with Ken Jenkins, Clyde Kusatsu, Tami-Adrian George, and Bart McCarthy).
Martin performed stunts in the action thriller Dusting Cliff 7 (1996), the thriller The Glimmer Man (1996, with Bob Gunton and Nikki Cox), the comedy Jane Austen's Mafia! (1998, starring Billy Burke), and the sport comedy BASEketball (1998). In addition he portrayed an ice thug in Joel Schumacher's sequel Batman & Robin (1997, alongside Steve Blalock, Mark Chadwick, Jim Palmer, Chris Sayour, and Paul Sklar), a guard in the comedy My Favorite Martian (1999, starring Christopher Lloyd, Wallace Shawn, and Ray Walston), a bartender in the comedy Now You Know (2002, with Todd Babcock, Earl Boen, and Joel Brooks), and the character Bailey in the action drama The Rain Makers (2005, with Ray Wise and Tim Sitarz).
Since 2002, Martin served as producer and production manager for the Skills for Actors series (2002) and feature films like Warrior (2002, with Blair Valk), Nola (2006), Pineapple (2006), and Red Ridge (2006). He worked as executive producer on the sport documentation Ultimate Texas Showdown (2006) and the television show Combat Fighting Championships (2007), and produced more recently the drama Bridge (2009).