Lassie, Once was a PUP that starred in the popular 1950s television series of the same name. The show followed the adventures of a female Rough Collie and her human family, the Millers. Lassie was portrayed by a succession of male Rough Collies, the most famous of which was Pal. The show ran for 17 seasons and was one of the longest-running shows in television history. The term 'Lassie, Once' is a reference to the original PUP that starred in the show.