(written from a Production point of view)
Derek Mears is a stuntman and stunt actor who played an Orion guard in the Star Trek: Enterprise episode "Borderland". He received no on-screen credit for this appearance. Mears was the first choice for playing the long faced bar alien in J.J. Abrams' Star Trek but was unable to shoot his part because of his time schedule. He recommended Douglas Tait who got this part. 
Mears always plays creepy or large aliens, mutants, or outsiders and is specialized in wearing werewolf and vampire prosthetics.
Among his resume are films such as The Demolitionist (1995, with Dana Dru Evenson), Men in Black II (2002, with Jack Kehler, Mary Stein, Kevin Grevioux, Paige Brooks, Ransom Gates, and Gail Monian), Signs (2002), The Haunted Mansion (2003, with Wallace Shawn, Rachael Harris, and Michael McAdam), Cursed (2005, with Michelle Krusiec, Brian Avery, Joni Avery, Paul Eliopoulos, Anita Hart, Angela Meryl, Boni Yanagisawa, and Alex Chansky), two of the Pirates of the Caribbean films (2003 and 2006, with Tom Morga), World Trade Center (2006, with Jude Ciccolella, Tom Wright, Donna Murphy, Scott Leva, and Thom Williams), and The Hills Have Eyes II (2007, with Michael Bailey Smith and Jeff Kober).
Mears' also appeared in several television series such as V.I.P. (1999, with Lisa LoCicero, Faith Minton, and Karen Sheperd), ER (2000, with Lily Mariye, Joanna Miles, Scott MacDonald, and Christopher Michael), Alias (2001), Charmed, Angel, C.S.I. New York (2005, with Eugene Collier), and My Name is Earl (2006, directed by Marc Buckland).
He filmed stunt work for the sports comedy Semi-Pro alongside stunt performers Shauna Duggins, Ian Eyre, and Stacey Carino, and the fourth installment of Indiana Jones, Indiana Jones and the Kingdom of the Crystall Skull, also alongside Shauna Duggins and Jon Braver, Lauro Chartrand, Kevin Derr, and Gary Wayton. Both films were released in 2008. Mears has also acted in several short films and short lived series, such as Time Belt and Wade and Eric sold a Movie for Channel 101 and the short-lived comedy TV series created by the Channel 101 Community, Acceptable TV.