Actor Russell Johnson, who played The Professor on "Gilligan's Island," has died.

He was 89.

Johnson's agent told Fox News that the actor passed away at his home in Washington State on Thursday morning of natural causes, with his wife and daughter by his side.

Johnson's co-star Dawn Wells, who played Mary Anne on the show, posted on her Facebook page: "My 2 favorite people are now gone. The professor past (sic) away this morning. My heart is broken."

"Russell was a true gentleman, a good father, a great friend, and 'the rest,'" Wells wrote.

Wells and Tina Louise, who played Ginger, are the show's last two surviving cast members.

"I was very saddened to hear of the passing of Russell Johnson," Louise said in a statement sent to FOX411. "He will always be in our hearts and remembered as part of American pop culture history as 'Gilligan's Island' lives on through ME TV and TV Land. He will be missed."

Johnson starred on "Gilligan's Island," a classic TV comedy about a mismatched set of castaways stranded on a deserted island, from 1964 to 1967.

His character, high school science teacher Roy Hinkley, built generators and other gadgets out of scraps of junk found on the island. Johnson later joked that the one thing The Professor never figured out how to do was to fix the leaky boat so the group could get back to civilization.

During its three-season run on CBS, critics repeatedly lambasted the show as insipid. But after its cancellation in 1967, it found generations of new fans in reruns and reunion movies.

One of the most recent of the reunion films was 2001's "Surviving Gilligan's Island: The Incredibly True Story of the Longest Three-Hour Tour in History," in which other actors portrayed the original seven-member cast while Johnson and two other surviving cast members narrated and reminisced.

In a 2004 interview, Johnson analyzed the show's lasting appeal.

"Parents are happy to have their children watch it," he said. "No one gets hurt. No murders. No car crashes. Just good, plain, silly fun — that's the charm."

He admitted he had trouble finding work after "Gilligan's Island," having become typecast as the egg-headed professor. But he harbored no resentment for the show, and in later years he and other cast members, including Bob Denver, who had played the bumbling first mate Gilligan, often appeared together at fan conventions.

He also appeared in more than two dozen feature films, including "MacArthur," ''The Greatest Story Ever Told" and cult science fiction favorites such as "It Came From Outer Space." In the 1953 Western "Law and Order," he took part in a gunfight with the film's star, Ronald Reagan.

Although he didn't work as often after "Gilligan's Island," Johnson remained active into the late 1990s, appearing on such shows as "My Two Dads," ''Dynasty" and "Newhart."

The future actor was part of a family of seven children raised in Ashley, Pa.

He joined the Army Air Corps during World War II and served as a B-24 bombardier on missions over the Pacific war zone, breaking his ankles in 1945 when his plane was shot down over the Philippine island of Mindanao. He was discharged as a first lieutenant in November 1945, having earned a Purple Heart and other medals.

Upon his discharge, Johnson enrolled at the Actors Lab in Hollywood under the GI Bill. Fellow actor Paul Henreid saw him in a play there and landed him a role as a villain in the film "For Men Only." Until "Gilligan's Island," the ruggedly handsome Johnson often played villains.

He married actress Kay Cousins after leaving the Army, and the couple had a son, David, and a daughter, Kim. His wife died in 1980, and his son, a prominent Los Angeles AIDS activist, died of AIDS in 1994.

After remarrying, Johnson and wife Constance Dane moved to Bainbridge Island, Wash., in 1988.

"We didn't intentionally set out to move to an island," the actor, noting the irony, told a reporter in 1993. "We'd lived in Los Angeles for 40 years and just wanted to get away from the heat, the smog and crowds."

From the island he often took a ferry to Seattle to do voice-overs for radio commercials.

It was also on Bainbridge Island that Johnson wrote the memoir "Here on Gilligan's Isle."

Survivors include his wife and daughter.

The Associated Press contributed to this report.