(written from a Production point of view)
John Hugh McKnight (born 26 August 1939; age 82) is an actor and stuntman who appeared in several episodes of Star Trek: The Original Series for which he received no credit. In 1979 he received credit as stunt performer on Star Trek: The Motion Picture.
McKnight was specialized in driving stunts and was a member of Bill Young's Precision Driving Team. 
Among his stunt resume are the films Speed (1994, with Alan Ruck, Richard Lineback, Carlos Carrasco, Jordan Lund, Patrick Fischler, Bruce Wright, Robin McKee, and stunts by Scott Wilder, Eddie Yansick, Janet Brady, Jophery C. Brown, Gary Epper, Tommy J. Huff, Eddie Mathews, Patricia Tallman, Chuck Hicks, and Jimmy Ortega) and Gone in Sixty Seconds (2000, with Michael Owen, Scott Burkholder, Tim de Zarn, Ken Jenkins, and stunts by Steve Blalock, Janet Brady, Jennifer Caputo, Eugene Collier, Eddy Donno, Kenny Endoso, Andy Gill, Jim Halty, Freddie Hice, Kane Hodder, Tommy J. Huff, Jeff Imada, Joel Kramer, Johnny Martin, Rusty McClennon, Johnny C. Meier, Alan Oliney, Manny Perry, Denney Pierce, and Merritt Yohnka)
As an actor, McKnight worked in the background of various episodes of The Love Boat (1977-1978), Dallas (1978), Charlie's Angels (1979), Fantasy Island (1982), Hart to Hart (1983-1984), Falcon Crest (1983-1986), Dynasty (1984-1988), The Colbys (1985-1986), and Knots Landing.
During filming of the science fiction comedy Airplane II: The Sequel in 1982, McKnight was among the group of extras who were converted from SEG to SAG members during filming. Others include Bo Ching and Nick Trisko. The film also features Trek performers Lloyd Bridges, William Shatner, John Hancock, Louis Giambalvo, Sam Anderson, Gary Faga, Bruce French, Marcy Lafferty, Louise Sorel, Earl Boen, Mel Gold, Gregory Itzin, Danny Nero, John Paragon, Frieda Rentie, George Sasaki, Debra Dilley, and Ilona Wilson.