(written from a Production point of view)
David Wendler (born September 1935; age 85) is a retired huntsman, stunt and race rider who served as horse riding stunt double for William Shatner in the two Star Trek feature films Star Trek V: The Final Frontier and Star Trek Generations. His costume from the latter film was sold off on the It's A Wrap! sale and auction on eBay although the name tag misspelled his name as David Wrendler. 
Born on a farm in Collinsville, Illinois, Wendler joined the Army at the age of seventeen and served two years as a Combat Engineer. He completed his military career at the Hunter Liggett Army Base in Northern California with the rank of a seargent. In 1953, Wendler joined his brother-in-law Clyde Kennedy who was working as a famous horse trainer on the West Coast and met Dan Daily, who brought him into the hunting club West Hills Hounds.
Over fifty years Wendler served as huntsman for the West Hills Hounds, a hunting club in California, with famous members such as Ronald Reagan, Walt Disney, Spencer Tracy, and John Huston. In addition, he was among the top horse race riders for four decades, winning several titles and prices in the categories steeplechase and point-to-point races. In the late '90s he retired from the active horse riding.
A member of the Screen Actors Guild since 1958, Wendler appeared in several films and television series, including the comedy Auntie Mame (1958, with stunts by Robert Herron), the drama The List of Adrian Messenger (1963), the comedy Do Not Disturb (1965), the musical remake Mame (1974, with Bruce Davison, Barbara Bosson, and stunts by Bennie E. Moore, Jr.), and the Murder, She Wrote episode It's a Dog's Life (1984, with Lenore Kasdorf).
Wendler also doubled actors and their horse work. Beside Shatner, he was the riding double for Steven Seagal in the 1994 action thriller On Deadly Ground, which featured fellow Star Trek stunt performers Ken Bates, Tony Brubaker, Keith Campbell, Phil Chong, Phil Culotta, Jeff Imada, Clint Lilley, Tom Morga, Mic Rodgers, Lincoln Simonds, and Jim Wilkey.