Russell auditioned for the role of neurosurgeon Ben Casey in the 1961 medical drama Ben Casey, but he lost out to Vince Edwards.
Russell's daughter, Kim Johnson, briefly made it into show business starring in movies such as The Great Skycopter Rescue, Looker, Priest and Antwone Fisher.
He is currently married to Constance Dane, and has one stepson with her. He was previously married to Kay Cousins Johnson until she died. He had two children with her.
Russell is left-handed.
Unlike the Professor, whom he played on Gilligan's Island, Russell said he wasn't that bright in grade school. In fact, he was held back.
Russell enlisted in the Air Force in World War II. Because of all the experience he had, he was highly recognized for what he did. Upon returning home, he joined the Army Reserves.
Russell's son, David, died of AIDS. Since his sons diagnosis, Russell has been a devout volunteer, working full-time organizing fundraisers for research.
Russell, in character as the Professor, has appeared at least once with scientists at the Nobel Prize ceremony.
In the first season of Gilligan's Island, the theme music stated every main cast member's character but Russell and Dawn Well's characters. They were stated as "all the rest". This was because their contract were the only ones saying their names didn't have to be included. This started a campaign to get their names in the theme. It was unsuccessful until the shows main Bob Denver sided with them, making it so from season 2 onwards, Russell and Dawn's characters were mentioned.
Russell, and his fellow Gilligan's Island cast members, don't get paid royalties when re-runs air.
Like his co-star Alan Hale, Russell welcomes people calling him The Professor and is very friendly when they call him that.
Most likely to prevent fans from correcting him, Russell made Gilligan's Island creator Sherwood Schwartz promise him that any scientific statements he made on the show be researched and proved accurate.
When auditioning for Gilligan's Island, Russell was asked to take off his shirt but he refused. Because he showed a lot of talent, they decided to cast him despite that.
Russell once appeared in a Twilight Zone episode in which he played a professor. He then played a professor in Gilligan's Island, the show that made his name a lot more recognized.
Russell never had any ambitions to be an actor until he was "spotted" by Paul Henreid.
Whilst in high school, he was a member of the National Honor Society.
Russell wrote a book about Gilligan's island titled "Here on Gilligan's Isle"
Russell: Old actors never die, they don't even fade away. They're always available.
Russell: I was at a speaking engagement for MIT and I said the Professor has all sorts of degrees, including one from this very institution! And that's why I can make a radio out of a coconut, and not fix a hole in a boat!