Gilligan Who?

Nearly everyone who has ever watched television is the western world is at least passingly familiar with Gilligan's Island. The series about seven castaways on an uncharted island ran on CBS for three years in the mid-1960s and has since become one of the most popular syndicated shows of all time and a mainstay of American popular culture. We revel in dissecting the show's minutiae, pondering such questions as "Why did the Howells bring suitcases full of money on a three-hour tour?" and "How come Gilligan wears the same clothes every day, but they never get dirty or torn?" The subject of one of the more enduring trivia questions over the years has been "What was Gilligan's full name?" Was 'Gilligan' his first name or his last name? And what was his full name?
A few events in the early 1990s spurred the claim that Gilligan was a surname, and that the character's first name was "Willy": TBS finally aired the pilot of Gilligan's Island (an episode that had never been broadcast) in 1992, and TV Guide announced in 1993 that it had discovered (from an early press release) that Gilligan's first name was supposed to be "Willy." Somehow the pilot, the first regularly-broadcast episode, and the TV Guide claim became conflated in the public's mind, producing a garbled and oft-repeated bit of Internet trivia:
Gilligan of Gilligan's Island had a first name that was only used once, on the never-aired pilot show. His first name was Willy. It was mentioned once in the first episode on their radio's newscast about the wreck. Some of the confusion here stems from the fact that the familiar group of Gilligan's Island actors did not all appear in the pilot episode. Before the series went into production, the part of the Professor was re-cast with a new actor, and the characters named Ginger and Bunny (both secretaries in the pilot), were transformed into a movie star and a small-town farm girl and re-cast with new actresses as well. Because of this change in casting, the pilot was unusable as a regular-season episode and was not broadcast until TBS finally aired it in
1992.
The first episode ("Two on a Raft," first aired on 26 September 1964) opened with the castaways shipwrecked on the island, and the details of how they came to be there (the basis of the pilot episode) were not shown. In order to provide the viewing audience with some background information about the characters, therefore, a scene in which the castaways listen to a radio broadcast about themselves was inserted into the first episode. The broadcast informed us that the Skipper was an "old salt in these waters"; that Thurston Howell was "one of the world's wealthiest men" (and, contrary to the theme song, a billionaire rather than a mere millionaire); that Mrs. Howell was a "socially prominent international
hostess"; that Mary Ann was from Winfield, Kansas, and worked at the Winfield general store; that Ginger "boarded the boat after a nightclub singing engagement still wearing the evening dress from her last performance"; and that the Professor was a "research scientist and well-known Scoutmaster." The broadcast mentions the characters' full names as well:

Jonas Grumby (Skipper)
Roy Hinkley (The Professor)
Thurston Howell III (Mr. Howell)
"Lovey" Howell (Mrs. Howell)
Ginger Grant (Ginger)
Mary Ann Summers (Mary Ann)
The broadcast also said only that the crew included a "young first mate named Gilligan." No other information about the character was provided, and no episode ever mentioned any other name for the Gilligan character.
So, as far as the show was concerned, Gilligan had but a single name. No other name was ever associated with character within the context of the series, and whether 'Gilligan' was his given name or his surname was never established. Some conceptual material for the series did make reference to the name 'Willy Gilligan,' which indicates that Gilligan's Island creator Sherwood Schwartz did give some consideration to a full name for the character, and that 'Gilligan' was once considered as being a surname. However, that full name was apparently one of the many details that never made it past the conceptual stage and into the show. Moreover, when Sherwood Schwartz later explained how he came to choose the characters' names, he made it clear that 'Gilligan' had to have been the character's first name, because the Howells were the only characters ever referred to by their last names: In a further effort to make the characters prototypes rather than completely flesh and blood, I decided to call them only by first names or nicknames — excepting Mr. and Mrs. Thurston Howell III, of course, because that would have been out of keeping with their characters.
But if 'Gilligan' was the character's first name (as indicated by the above quotation), then his full name couldn't possibly be 'Willy Gilligan,' and we're left with mutually exclusive explanations. The best sense we can make out of it is that series creator Sherwood Schwartz briefly considered naming his main character 'Willy Gilligan,' thought better of it, and decided to use 'Gilligan' alone as a first name. (Other elements from the original series treatment were also dropped along the way, such as the idea that Gilligan was an ex-Navy cook who knew nothing about the sea but, desperate for a job, convinced the Skipper that he was an experienced seaman. Instead, the show's theme song simply cast Gilligan as a "mighty sailin' man.")
Ruminations that took place long after the original series was cancelled have added to the confusion. Actor Bob Denver, who played the role of Gilligan, suggested that the idea of 'Willy' as a first name for the character was merely speculative — something that came up in idle conversation about a name that might have been chosen if the character ever needed a full name: One of TV's great bits of trivia is Gilligan's first name. None was ever revealed on the show, but years later on a talk show Bob Denver claimed that he had talked the matter over with the show's creator/producer Sherwood Schwartz, and they decided that if Gilligan ever did need a first name, it would be "Willie." But Sherwood Schwartz maintained that Bob Denver considered 'Gilligan' to be the character's first name:
To this day, almost every time I see Bob Denver we still argue. He thinks Gilligan is his first name, and I think it's his last name. Because in the original presentation, it's Willy Gilligan. But he doesn't believe it, and he doesn't want to discuss it. He insists the name is Gilligan. So, there's no right answer for this one. No, no name other than 'Gilligan' was ever used for the title character in Gilligan's Island, not even in the original pilot. Yes, there is evidence that series creator Sherwood Schwartz considered using the name 'Willy Gilligan' during the series' planning stages. On the other hand, there's also evidence that Schwartz ultimately decided 'Gilligan' was the character's first name, precluding the use of 'Willy Gilligan' as a full name. Pick your favorite explanation and run with it.

SOURCE: Snopes