Ian McKellen - first early film role - A Touch of Love 1969

I would say probably best known to American audiences as Magneto(X-Men Series) and Gandalf(Lord Of The Rings movies).
One of McKellen's first major roles on television was as the title character in the BBC's 1966 adaptation of David Copperfield, which achieved 12 million viewers on its initial airings. After some rebroadcasting in the late 60s, the master videotapes for the serial were wiped, and only four scattered episodes (3, 8, 9 and 11) survive as telerecordings, three of which feature McKellen as adult David. McKellen had taken film roles throughout his career—beginning in 1969 with his role of George Matthews in A Touch of Love, and his first leading role was in 1980 as D. H. Lawrence in Priest of Love,[30] but it was not until the 1990s that he became more widely recognised in this medium after several roles in blockbuster Hollywood films.[24] In 1969, McKellen starred in three films, Michael Hayes's The Promise, Clive Donner's epic film Alfred the Great, and Waris Hussein's A Touch of Love (1969).