American actor (1944 to 1999), well over seven feet tall, who played the huge alien prisoner who picks a fight with Kirk on Rura Penthe in Star Trek VI: The Undiscovered Country.
John Bloom was an exceptionally tall American actor who specialised in monsters and giants, including the Frankenstein creature in Dracula vs. Frankenstein and a mutant in The Hills Have Eyes Part II.
In Star Trek VI: The Undiscovered Country (1991) he played the towering horned inmate of the Rura Penthe penal colony who confronts the newly arrived Kirk. With no universal translator, Kirk cannot understand the challenge and is being badly beaten until a lucky kick to the creature's knees brings it down.
The shapeshifter Martia then explains that those were not its knees. The defeated alien afterwards treats Kirk with respect.