Chuck Cunningham from “Happy Days”
Chuck Cunningham was the eldest sibling in his family on “Happy Days,” and he was played by Gavin O’Herlihy. But he was later replaced by actor Randolph Roberts. The most obvious difference between the men was that one was a redhead and the other wasn’t. But this change passed by the notice of many viewers, because the character was written out of the show after the first season.