Jeffrey Weissman
Jeffrey Weissman plays George McFly in Back to the Future Part II and Part III, and not in the first film. That is an unusual line on a resume, and it is the fact that follows him: two enormously popular sequels, a character the audience already knew intimately, and no share of the original.
The rest of the catalog is small and mostly from the 1980s. Teddy Conway in Pale Rider in 1985, a young man in Twilight Zone: The Movie in 1983, a backstage dancer in Crackers in 1984, an uncredited voice in Heathers. Wikipedia adds guest spots on Scarecrow and Mrs. King, Max Headroom, Dallas, Diagnosis: Murder and Saved by the Bell, none of which the catalog carries. He has also appeared as himself on Creature Features.
Seven credits is a thin filmography by any measure and there is no point pretending otherwise. What there is instead is a genuinely odd piece of film history attached to a face millions of people can picture.
Movies (6)
TV (1)
Where to start with Jeffrey Weissman
Two films carry this filmography and you have almost certainly seen them both. Back to the Future Part II is the one to watch with the casting question in mind, since the whole sequel is built on your memory of the first.
Back to the Future Part III gives him the loosest version of the character and, in the western setting, the most room to play.
Beyond that, Pale Rider is by some distance the best film he is in, a stark western where he has a real supporting part rather than a walk-on. Twilight Zone: The Movie is a curiosity, Heathers an uncredited voice you will not spot, and Creature Features is him as himself, talking about the work.