Though they were marooned, the shipwrecked characters of "Gilligan's Island" often found themselves in fantastical scenarios, thanks in part to the show's goofy dream sequences. One such sequence, in the season 3 episode, "Lovey's Secret Admirer," involved the titular Lovey, aka Mrs. Howell (Natalie Schafer) having a Cinderella-like dream. Instead of a fairy godmother, Gilligan himself (Bob Denver) appeared as her fairy godfather.
His costume had a distinct design with a yellow-and-green robe, decorated on the chest with what looked like an eye in the middle of a sun. As Silver Age Television notes, this same costume popped up later in an episode of the second season of "Star Trek."
The costume was worn by actor Theodore Marcus, who portrayed the alien Korob in the episode "Catspaw." When Korob makes his entrance, he does so in an appropriately magical fashion. Captain Kirk (William Shatner), Mr. Spock (Leonard Nimoy), and Dr. McCoy (DeForest Kelley) affect a daring escape from a dungeon on an alien planet, only to find themselves transported into Korob's throne room in the blink of an eye. And there we meet one of the villains of the episode ... wearing the same costume as Gilligan's fairy godfather.
And while we're at it-
https://heavy.com/entertainment/star-trek/gilligans-island-reference-voyager/
People notice the strangest little details in these shows. It always amazes me.