Glenn H. Randall Sr. (1908-1992) was a professional horse trainer, best known for training the horse Trigger for the television series The Roy Rogers Show.

He developed over 30 hand commands to which the palomino responded.

[1][3] Starting months before photography began, he trained around 40 horses for Ben-Hur, including the four whites (Altair, Rigel, Antares, and Aldebran) that Charlton Heston drove in the chariot race.

[4] Glenn Sr. later worked as a wrangler on the 1979 film The Black Stallion and its 1983 sequel The Black Stallion Returns.

His son Glenn H. Randall Jr., also known as "J.R.", was also a horse trainer as well as a stunt performer, stunt coordinator, and second unit director who was active from 1959 to 2000.