There were some earlier "Lassies," in literature of the 1800's, as well as in silent films. 'Eric Knight', a British-born author, wrote a Lassie character in a short story in 1940, then expanded it to a novel called "Lassie Come Home," which became the first Lassie sound film. The original "modern" Lassie, or at least the animal character that we know today, was first played by a male collie named Pal in
A Força do Coração (1943). Pal is listed on the IMDb as
Pal, and played Lassie in all of the early sound films. His descendants played in the TV series and in most Lassie films and TV appearances since.