Trying to understand the logic behind movie casting is a pretty thankless task at the best of times, because it's such a subjective art whereby a director or casting assistant sees something in a performer that nobody else does - whether for better or worse.
And while a killer audition will often give an actor a huge advantage over their competition, sometimes filmmakers end up casting major, iconic roles for the most unexpected of reasons.
The director may have noticed the most subtle acting flourish or eccentric physical tic during an audition, perhaps the actor proved themselves to harbour the inner qualities of the character in their real life, or maybe the performer resorted to flat-out deceiving the director in a fiendishly clever way.
Whatever the reason, these 10 roles were cast by totally unconventional and unexpected means, confirming that no matter how much effort an actor puts into an audition - or doesn't, in fact - there's no accounting for what a director is really looking for...
10. Ben Affleck Had The Same Smile In Every Paparazzi Photo - Gone Girl
It's no secret that David Fincher is incredibly particular about the casting of his movies, and after he teased a killer performance out of Justin Timberlake in The Social Network, there was no reason to ever doubt him.
Ben Affleck was cast in the lead role of Nick Dunne for Fincher's 2014 thriller Gone Girl, playing a husband whose wife (Rosamund Pike) disappears, causing him to become the prime suspect.
Fincher didn't merely cast Affleck for his star profile, though, but because of one specific reason - his smile.
Fincher sought out actors for the part by scouring Google, and noticed a peculiarity about the way the actor smiled in paparazzi pictures which made him perfect for Gone Girl's unforgettable press conference scene, where Nick smiles for the cameras and is endlessly pilloried by the media for it. Fincher said:
"You cast movies based on critical scenes. In Gone Girl there's a smile the guy has to give when the local press asks him to stand next to a poster of his missing wife. I flipped through Google Images and found about 50 shots of Affleck giving that kind of smile in public situations. You look at them and know he's trying to make people comfortable in the moment, but by doing that he's making himself vulnerable to people having other perceptions about him."
Affleck's million-dollar smile has probably won him countless roles over the years, but never in a way quite like this.