I know that Bruce Willis became an icon when Die Hard was released in 1989 (he’s been an uncredited extra in a Paul Newman movie: the Verdict 7 years earlier in 1982). Same with Sylvester Stallone in Rocky (1976) which made him achieve stardom, 5 years earlier in 1971: he’s an extra in Klute (starring Jane Fonda & Donald Sutherland) during the scene they’re at a club as a disco dancer in the background (his appearance is uncredited).