Harry Palmer is the protagonist of a number of films based on the unnamed main character from the spy novels written by Len Deighton. Michael Caine played Harry Palmer in three films based on the four published novels featuring this character, and also later in two films not based on Deighton's novels.

The Ipcress File (1965)

Funeral in Berlin (1966)

Billion Dollar Brain (1967)

Bullet to Beijing (1995)

Midnight in Saint Petersburg (1996)

There is another, Spy Story (1976), but it stared Michael Petrovitch and the character is renamed 'Patrick Armstrong'.

More Info: en.wikipedia.org