Russell Johnson, the actor whose genius Professor Roy Hinkley was always one coconut away from inventing a way off "Gilligan’s Island," has died of natural causes. He was 89.

Dawn Wells, who played fellow castaway Mary Ann, said her friend passed away this morning after being in hospice for a short period of time.

"Russell was 100 percent a gentleman," she told "The Insider." "A genuine, dear, wonderful man."

Wells also took to Facebook to express her sadness.

The other person Wells was referencing was castmate Bob Denver, who died in 2005 at the age of 70.

Before his three-hour tour took a bad a turn, Johnson was a player in 1950s science-fiction classics "This Island Earth" and "It Came From Outer Space." He also scored two appearances on "The Twilight Zone" and acted opposite Ronald Reagan in the 1953 western "Law and Order."

Prior to acting, Johnson served in the Army Air Corps during World War II. He earned a Purple Heart when his plane was shot down over the Philippines in 1945.

Johnson was married three times, most recently to actress Constance Dane.

Speaking to Yahoo TV, Johnson's agent Mike Eisenstadt had fond memories of the small-screen star. "Great guy, very respectful, he loved his family," said Eisenstadt, who also represented Wells, Denver, and Tina "Ginger" Louise. The agent called the classically trained Johnson a "very positive guy" who loved his fans but chose to live away from Hollywood in Washington state. "He didn't want to be in that scene," he said.