(written from a Production point of view)
Gregory "Greg" J. Barnett is a stuntman, stunt coordinator, and director who served as Leonard Nimoy's stunt double in Star Trek IV: The Voyage Home and Star Trek V: The Final Frontier. In Star Trek IV, Barnett also performed stunts as a Starfleet technician. His costume from this appearance was sold off on the It's A Wrap! sale and auction on eBay.  In addition, he served as assistant stunt coordinator for the stunt scene aboard the USS Ranger.
His career as a stuntman began in the 1960s with stints on General Hospital and Days of our Lives and has covered 40 years with almost 300 stunt credits to his name including Jaws 2 (1978), Murder She Wrote, Terminator 2: Judgment Day (1991), Buffy: The Vampire Slayer (1997), Pearl Harbor (2001), Mission: Impossible III (2006), and Heroes (2006).
He served as stunt coordinator, second unit director, underwater photographer, and regular background actor on Baywatch. The show also featured Amy Wheaton, Chip Mayer, Albert Stratton, Christopher Pettiet, Steven Anderson, Lilyan Chauvin, Marci Brickhouse, and James Horan as guest stars, and Monte Markham as a regular character. He also appeared in The Ultimate Imposter (1979, with TNG/DS9's Rosalind Chao, Keith Andes, and Robert Phillips), Samurai (1979; with Michael Pataki, Don Keefer, Walt Davis, Bob Minor, Tom Lupo and Johnny Haymer), They Live (1988, with Jeff Imada, Thelma Lee, and Meg Foster), K-9000 (1991; with Judson Scott, Anne Haney, David Renan, Ted Barba, James H. Burk, Kenny Endoso, Jeff Imada, Dave Perna and Nicholas Shaffer; with more stunts by Lane Leavitt), and most recently a few episodes of 24 (2003).