Jonah Hill made his name as a comedic actor, but the role that got away could have been his breakout dramatic appearance. Today Jonah Hill is a multiple time Academy Award nominee but there was a time when he wasn't known for making those sorts of films. His breakout his serious drama was probably 2011's Moneyball but it could have been a year earlier, as it turns out he was very nearly in David Fincher's The Social Network, but the director didn't want him. According to Hill...
Low-key, David Fincher, or high-key, David Fincher didn't want me in Social Network. It was between me and Justin Timberlake for that part... Obviously [Fincher's] the man, but he was not having me. The studio wanted me, I think, and then Justin Timberlake was amazing in it.
It seems that while there were some people interested in having Jonah Hill play Napster founder Sean Parker in The Social Network, director David Fincher was sold on getting Justin Timberlake in the role.
Jonah Hill says he has several other stories about roles he didn't get, though he doesn't go into too much detail on the others while appearing on The Bill Simmons Podcast. He only mentions that he was passed over for this particular role. Hill makes it clear he doesn't hold anything against the director for not casting him in the movie, saying he's only met Fincher once and the director was nothing but nice.
While Jonah Hill's career certainly didn't suffer for not getting the Social Network, as he would go on to make Moneyball and be nominated for an Oscar, he does admit that, of all the roles that he lost out on, that movie is the one that he still really wishes had worked out.
Social Network is the one that I was actually like years later was like, 'Fuck, like I'm so bummed.'
The reason that Jonah Hill appears to be so bummed about not getting the role is that he absolutely loves the movie. He says it's a movie he could watch and enjoy on a loop. He thinks Justin Timberlake did great with the performance that could have been his and he especially calls out the Oscar-winning score for the movie, which he mentions influenced how he wanted the music to be handled in his own directorial debut, Mid90s.
You can see how Justin Timberlake handled the role in question in the clip below.
We almost certainly would have had a very different version of Sean Parker had Jonah Hill ended up in the role instead of Justin Timberlake. Still, knowing now how great Jonah Hill is, I would love to have seen what he would have done with such a part. You can see Jonah Hill's Mid90s in theaters now.