http://www.notstarring.com/actors/smith-will 
 
Charlie and the Chocolate Factory 
Smith was considered to play Willy Wonka. 
Actor who got the part: Johnny Depp 
 
Hotel Rwanda 
Smith was considered for the lead role of Paul. 
Actor who got the part: Don Cheadle 
 
K-PAX 
Smith was originally set to play the role of Prot. 
Actor who got the part: Kevin Spacey 
 
Man on Fire 
Will Smith was considered for the role of Creasy. 
Actor who got the part: Denzel Washington 
 
The Matrix 
Will Smith turned down the lead role, admitting later that he had no regrets because "Keanu was brilliant as Neo." 
Actor who got the part: Keanu Reeves 
 
Men in Black 
Will Smith Originally turned down his role in Men in Black, however his wife eventually talked him into reconsidering. 
Actor who got the part: Will Smith 
 
Mr. & Mrs. Smith 
Smith was considered to play John Smith. 
Actor who got the part: Brad Pitt 
 
Osmosis Jones 
Will Smith's people said he expressed an interest in the part, but in the end he schedule didn't permit it. 
Actor who got the part: Chris Rock 
 
Phone Booth 
Will Smith turned down the role of Stu. 
Actor who got the part: Colin Farrell 
 
Snake Eyes 
The role of Commander Dunne was offered to Will Smith, but the studio thought he wanted too much $$. 
Actor who got the part: Gary Sinise 
 
A Star Is Born 
Talks of remaking A STAR IS BORN circled for years in Hollywood. Will Smith and Whitney Houston were attached at one point. Project never got off the ground. 
Actor who got the part: Project Never Got Made 
 
Stuck on You 
Originally meant to costar with Woody Allen as conjoined twins in the Farrelly bros. comedy. 
 
The Truth About Charlie 
Smith was considered to play Joshua Peters but turned it down because he was still shooting Ali. 
Actor who got the part: Mark Wahlberg