TV afforded Nelson better star treatment in the 50s beginning with roles in several live dramatic anthologies of the period including "The Chevrolet Tele-Theater", "Pulitzer Prize Playhouse" and Starlight Theater. He is reputed to be the first actor to portray super secret agent James Bond--albeit as an American--in a TV adaptation of Ian Fleming's novel "Casino Royale" on the late 50s anthology series "Climax!". Nelson headlined his own series, playing US government agent Bart Adams, a suave master of disguises, on the Cold War-themed "The Hunter" (CBS, 1952; syndication, 1952-54). He proved even more adept as a sitcom lead on "My Favorite Husband" (1953-55). Nelson continued popping up on the small screen in dramatic anthologies, specials, TV-movies and guest shots, though with decreasing frequency since the mid-70s. He has been in only a few features since 1970, receiving his last significant exposure in Stanley Kubrick's "The Shining" (1980) as the hotel executive who hires Jack Nicholson as a caretaker.
In contrast, Nelson had been a theater staple since the late 40s, with Broadway credits including "Light Up the Sky", "The Rat Race", "The Moon is Blue" and "Cactus Flower". He was nominated for a 1978 Tony for his lead role in "The Act", a Broadway musical directed by Martin Scorsese and co-starring Liza Minnelli. The mid-80s found Nelson in the national and Broadway companies of "42nd Street".