Johnson, who was the last surviving male star from sitcom, died of kidney failure at his home with family by his side.
He portrayed the Professor in the classic comedy from 1964-67, appearing in 98 of the show’s 99 episodes.
“He was a gentleman, very kind,” Johnson’s agent, Mike Eisenstadt, said. “He was very smart and very respectful. He was a nice, normal guy.”
Johnson worked regularly in TV and films for more than 40 years, appearing on The Twilight Zone, Lassie, The Lone Ranger, The Jeffersons, Newhart, Gunsmoke, Dynasty and Roseanne.
Films credits included the cult sci-fi classic It Came From Outer Space plus The Stand at Apache River and Tumbleweed.
Former cast mate Dawn Wells, who played Mary-Anne, wrote on Facebook:
“My 2 favorite people are gone now. The Professor [passed] away this morning,” along with a pic of her, Johnson and Denver. “Russell was a true gentleman, a good father, a great friend, and ‘the rest.’ I love him and shall miss him. My heart goes out to Connie and his daughter Kim. I love you.”
Johnson once wrote on his own website, “I think, what I love most at this point in time in the long life of Gilligan’s Island is the positive, intelligent nature of longtime Gilligan aficionados.
“It amazes me. I have received mail throughout the years from young viewers from all over the world, year after year, who were so influenced by the Professor’s smarts that they became science buffs and are now real professors, doctors and scientists. It makes me proud.”