Possible Clues:

• “Gilligan’s Island” co-star
• Co-star of Bob Denver on 'Gilligan's Island'
• "The Man in the Iron Mask" star
• Player of the Skipper on 'Gilligan's Island'
• Jr. of 'Gilligan's Island'
• "Gilligan's Island" co-star
• Comet co-discoverer who shares his name with a father-and-son acting pair
• Frequent Errol Flynn co-star whose son played Gilligan's skipper on TV
• Portrayer of Gilligan's skipper