William Blackburn was a background performer who sat at the Enterprise helm and navigation stations as Lieutenant Hadley throughout The Original Series and also served as DeForest Kelley's stand-in.
Bill Blackburn was one of the most frequently seen faces of The Original Series, although he almost never spoke. A former professional ice skater, he was hired as DeForest Kelley's stand-in and was then used week after week as the relief helmsman or navigator Lieutenant Hadley, a name finally spoken aloud in A Piece of the Action.
Because he was always on the set he was given a string of odd jobs in costume. He was the White Rabbit hurrying past McCoy in Shore Leave, wore the Gorn head for close-ups in Arena, and lay in for the unfinished android body in Return to Tomorrow.
Blackburn also shot silent home-movie footage behind the scenes, which was later released and has become a valued record of the production.