Robin Masters was a fictional character on the American television series Magnum, P.I. He was the alleged celebrity author/multi-millionaire owner of Robin's Nest, the estate mansion where Magnum and Higgins resided, and was the owner of the Ferrari that Magnum drove. Much like the character of Charlie in Charlie's Angels, Robin Masters remained an unseen character. One episode of the series described Masters as such: the voice of Orson Welles, and the body of Truman Capote. Welles was called on several times to "portray" the voice of Robin Masters.

There is much speculation as to the exact identity of Robin Masters. Near the end of the series, it was implied that Higgins and Robin Masters might be the same person; however, in the context of the series as a whole, numerous story lines in preceding episodes raise question to the logic supporting this idea.

If Higgins was actually the "real" Robin Masters, his identity was kept secret from Magnum. In the series finale, Higgins proclaims to being Robin Masters, but at the very end of the episode, he whimsically tells Magnum that he had lied about being Robin Masters, leaving viewers to wonder which version was the truth. Since the writers of the show never revealed Masters' "true identity" to the audience, it will most likely never actually be known.

In the beginning of season 1, episode 4, we hear Higgins answer a phone call and address the caller as "Mr. Masters." Since our view is limited to a television screen, we have no way of knowing whether someone was in the room with Higgins and he was continuing the charade for their benefit or whether he was actually talking to Masters. If the former is the case, it brings up the question: who was the caller?

Also, in season 1, episode 17, Thomas Magnum actually helps the man referred to as Robin Masters get out from a helicopter that has landed on the estate's lawn. Also, in 1982's episode entitled "Italian Ice", a young woman fondly recalls watching both Higgins and Robin Masters play chess with her father.

In an episode entitled "The Big Blow" (Season 3, Episode 22) a person, seemingly acknowledged as Robin Masters, appears with Magnum in a bedroom at the estate confronting a guest who shot several rounds from a gun into a figure on a bed, believing the figure to be Mr. Masters. When she is confronted by Magnum and this other person, she addresses this other person in a manner that indicates she recognizes him as Robin Masters.

In season 1, episode 17, a person identified as Robin Masters is on an airplane while Higgins is back at the Estate.

In season 6, episode 8, entitled "the treasure of Kalaniopu'u" Magnum mentions several times that he showed Robin some locations for a book on the island. This suggests that Magnum has actually met Robin in person.

In 1986's episode "Mad Dogs and Englishmen", Robin Masters fires Higgins because of some missing funds from Robin's account; Magnum speaks to Robin on the phone and Robin is seen from the side lying in a bed with a young woman in the room. Strangely, however, later episodes conveniently overlook these obvious clarifications in an effort to play on speculation that Higgins was Robin Masters. Such as 1986's episode "Paper War", in which Higgins calls the Ferrari "my Ferrari" and differentiates between "The Memoirs and The Novels" referring to his memoirs and Robin's novels, leading Magnum to accuse Higgins of hiring an actor to portray Robin Masters so that Higgins could indulge his secret identity without suspicion.