Russell Johnson (born 1924) played The Professor (name was eventually revealed to be Roy Hinkley) for 13 seasons on the beloved comedy Gilligan's Island. He had quite a successful television career, appearing on Black Saddle, The Twilight Zone, Lassie, Ironside and Gunsmoke. He also appeared in many films, but he is most famously known as one of seven stranded castaways.
Dave Madden (born 1931) played Reuben Kincaid, the manager for family musical group The Partridges on the hit sitcom The Partridge Family for three seasons. He later had a recurring role on Alice and appeared on other shows, including Bewitched, Happy Days, The Love Boat and Fantasy Island.
Rest in peace, gentlemen.