John Travolta - Welcome Back, Kotter Peter Sellers - The Return of the Pink Panther Guy Pearce - L.A. Confidential Malcolm McDowell - A Clockwork Orange or possibly Blue Thunder Jennifer Connelly - Career Opportunities Dan Ackroyd - Saturday Night Live
John Travolta – First saw him on the TV series Welcome Back, Kotter. But for movies, it would be Carrie (1976) but, at the time, he was a virtual unknown. Only in retrospect did people look back and say, “Wow, that was John Travolta.”
Peter Sellers - The Pink Panther (1963), followed closely by Dr. Stranglove (1964)
Guy Pierce – if you mean the actor from Memento, it is Guy Pearce and my first movie with him was L.A. Confidential (1997).
Malcolm McDowell – A Clockwork Orange (1971) – but I didn’t see the movie until 1985.
Jennifer Connelly – Some Girls (1988)
Dan Ackroyd - Aykroyd. The Blues Brothers (1980) if SNL on the TV doesn't count.