The Fat Man was a popular radio series during the forties and fifties. The Fat Man was Brad Runyon, a very large private detective. The character was supposedly created by Dashiell Hammett, but his involvement is not just hard to pin down, it's almost ethereal. Presumably the title was a play on his 'The Thin Man.' While the radio show was no Johnny Dollar or Richard Diamond, it compares favorably with the Sam Spade and Philip Marlowe serials of the time.
J. Scott Smart played the title role, also starring in a 1951 movie adaptation that included Rock Hudson, Julie London and famed circus clown, Emmet Kelly.
In 1959, Screen Gems made a tv pilot (click here to see it), The Fat Man: The Thirty Two Friends of Gina Lardelli. Robert Middleton did a fine job playing a somewhat more dignified Runyon than the radio show persona. Tony Travis, his Archie Goodwin, would have made a pretty good Archie. A lovely young Rita Moreno also features.
This pilot holds up pretty well some fifty five years later, which is not the case for an awful lot of pilots from the era. The show has some Nero Wolfe in it, and I thought of William Conrad and Cannon while watching as well. Go ahead and give it a watch.