1. Orson Welles - Citizen Kane
It's one thing to pick up an Academy Award on the strength of your very first performance (especially notable for a ten year old), but it's something else entirely to write, direct produce and star in your cinematic debut, then for it to go down in history as the greatest movie ever made. Whether or not you agree that Citizen Kane is the best movie of all time (I don't, but it's certainly up there) it's impossible to deny that Orson Welles managed to craft a film which was not only a huge step forwards in terms of technical innovation but also a radical reworking of the notion of biography and narrative structure. More importantly, it all holds together via the towering central performance from Welles that matches the sense of omnipotence - and arrogance - of the media magnate on which the character was based, William Randolph Hearst. The real tragedy, as any cinephile knows, is that unlike many of the other stunning debut performances featured on this list, Orson Welles didn't get the recognition he clearly deserved for this accomplishment, and instead spent his entire career almost as a pariah outside of the film industry circles. There have been fewer travesties of justice in the history of the movies. Are there any other exceptional debut performances missing from this list? Why not tell us about them in the comments?