Super Festivals from Ft. Lauderdale, USA · CC BY 2.0

Walter Koenig played Ensign Pavel Chekov across the original run of Star Trek and all six original-cast films, later voicing an aged version of the character in Star Trek: Picard -- a five-decade span for the role. Alongside acting, he built a parallel career as a writer, working on Land of the Lost and other 1970s and 80s television.