R.I.P. Russell Johnson - If there are coconuts in heaven, we will hear from the Professor again.

Actor Russell Johnson, best known as Professor in the 1960s TV sitcom "Gilligan's Island," died Thursday, his agent said. Johnson was 89. Johnson played the iconic role of Professor Roy Hinkley, whose scientific schemes to get the castaways rescued were always foiled by Gilligan's bumbling.

He died at his home in Washington, where he lived with his wife, Connie. She and their daughter, Kimberly, were at his side, said agent Mike Eisenstadt. Johnson is also survived by a stepson, Court, and a grandson, he said. Johnson worked up until his death, signing autographs over the holidays, said Eisenstadt. He called Johnson's death "unexpected." The chief deputy coroner in Kitsap County, Washington, told CNN that Johnson died from natural causes.

Johnson was "just a positive and nice guy" who always treated people with respect, his agent said. His acting career began in the early 1950s with many jobs as a character actor on television. He played Marshal Gib Scott in two seasons of "Black Saddle," a Western that ran in 1959 and 1960.

Johnson acted in dozens of television shows after the four seasons on "Gilligan's Island," but his career seemed stranded on its own island because of the popular sitcom role. A noteworthy big screen role was as a nuclear physicist in the 1955 science fiction film "This Island Earth." Johnson was in Ray Bradbury's 1953 sci-fi classic "It Came From Outer Space."

Before becoming an actor, Johnson served in the U.S. Army Air Forces during World War II. He was on a B-24 Liberator when it was shot down during a bombing raid over the Philippines in 1945, according to his official biography, and used his G.I. Bill benefits to pay for acting school after the war.

Johnson, in a 2004 interview for the Archive of American Television said the success of "Gilligan's Island, which he never expected to last more than the initial order of 13 episodes, was the result of the "great chemistry" of the cast.

Tina Louise, who played the glamorous Hollywood starlet Ginger on "Gilligan's Island said she was " very saddened to hear of the passing of Russell Johnson." "My prayers and condolences go out to his wife Constance and his family," Louise said. "He will always be in our hearts and remembered from Gilligan's island as part of American pop culture history. He will truly be missed."

Advice to young actors : Johnson's advice to young actors was to "prepare yourself." "Most of us have to really learn how to do what we do, and that takes some studying and being part of an acting group," he said. "Preparation is everything, and that means studying." Another important ingredient to acting success is perseverance, he said. "You can have all the talent in the world, but if you don't persevere, if you don't stick to it, it doesn't mean anything."

Actor Russell Johnson, best known for his role as the Professor on Gilligan’s Island, has died at the age of 89. Johnson was the last surviving male cast member of the series. By the time he was cast as the Professor—when he was still “Roy Hinkley” to his friends—Johnson had been in movies and TV for almost 15 years, appearing in several Westerns and sci-fi films, including a handful of B-movie classics like Jack Arnold’s It Came From Outer Space (1953), Roger Corman and Charles B. Griffith’s Attack Of The Crab Monsters (1957), and This Island Earth (1955). This Island Earth would be revived more than 40 years later as the feature-within-the-feature of Mystery Science Theater 3000: The Movie (1996). When Johnson makes his entrance in that movie, one of the MST3K crew pays tribute to his most famous role by immediately saying, “What’s this ‘and the rest’ crap!?”

In the early 1960s, Johnson began devoting more of his energy to TV work, with a regular role on the Western series Black Saddle and guest spots on such programs as Riverboat, The Twilight Zone, Route 66, Rawhide, Wagon Train, and Ben Casey. With his ruggedly handsome features and trim build, Johnson seemed a good bet to someday headline his own dramatic series, and he later said he took the job on Gilligan’s Island as a placeholder, never dreaming that it would last longer than 13 weeks. Premiering in 1964, the comedy ran for three years, and CBS had already notified the cast that they’d be picked up for a fourth when the network suddenly reversed itself and cancelled the show. (The show reportedly fell victim to the whims of CBS President Bill Paley, whose wife had just received word that her favorite show, Gunsmoke, had been canceled, and pressured him to make an executive decision to bring it back.)

Although Johnson continued to work in TV steadily throughout the 1980s and into the ’90s, like so many in the cast, he never fully shook his identity as the Professor—especially as Gilligan became a staple of syndicated reruns. For years, Johnson expressed frustration over the ceiling that his being identified as the Professor seemed to put over his career, but in later years, he seemed to have made his peace with it. “I am the Professor,” he said, “and that’s the way it is. The show has brought a lot of joy to people, and that’s not a bad legacy.”

After the series went off the air, Johnson reprised the character on two Saturday morning cartoon series, The New Adventures Of Gilligan (1974) and Gilligan’s Planet (1982) and a string of reunion TV movies (Rescue From Gilligan’s Island, The Castaways On Gilligan’s Island, The Harlem Globetrotters On Gilligan’s Island), as well as in Gilligan-centric episodes of ALF and Meego. He and his fellow surviving castaways also appeared on a 1995 Roseanne episode with the self-explanatory title, “Sherwood Schwartz—A Loving Tribute”. In 1993, Johnson published a book, Here On Gilligan’s Island, and a year later he promoted it on Space Ghost Coast To Coast. That appearance ended with the superhero turned talk show host blasting Johnson with his armband after Johnson asked him, “Are you Beavis or Butt-head?”