Remembered best for his role as Gort the robot in the 1951 science fiction movie The Day the Earth Stood Still, Martin is also notable for playing the Giant in several scenes that were later deleted from the 1957 movie The Incredible Shrinking Man.
Before being cast as Gort, he manned the door at Grauman's Chinese Theater in Hollywood.
Though he was well over seven feet tall, he was not terribly strong and, partly because of his cumbersome robot costume, was unable to lift actress Patricia Neal in a scene in The Day the Earth Stood Still.
Born Joseph Lockard Martin, Jr., he grew up in Pennsylvania and later lived and worked in Los Angeles, California. For the final decade of his brief life, he was married to Ethel Babcock.
He and Michael Rennie were both in the cast of The Day the Earth Stood Still.