Question: Who played Ellery Queen on television?
Televisionary: The mystery here is which incarnation you're talking about. However, as your tireless servant, I'll provide all the details I've got in my usual tedious fashion.
TV's first Ellery Queen, the mystery writer who helped his police-inspector dad solve crimes, was played by Richard Hart when The Adventures of Ellery Queen debuted on the DuMont network in 1950. After Hart suffered a fatal heart attack early the next year, Lee Bowman stepped in and the show jumped to ABC until its demise in late '52.
Hugh Marlowe, who played Queen on a radio show, brought the character back to the small screen two years later in a run of syndicated TV-movies before Lee Philips replaced him in the latter half of them.
Actor Jim Hutton (father of Timothy) played the sleuth in NBC's '70s version, which debuted in September 1975 and left the air a year later. (An additional trivia note: Magnum, PI's John Hillerman played Simon Brimmer, a rival detective in that iteration.)