It's hard to imagine anyone other than Keanu Reeves playing Neo in THE MATRIX at this point, but very early on in the development of the first film, the Wachowskis wanted Will Smith to play the lead. This isn't exactly a new revelation, but Smith recently posted a video on his YouTube explaining exactly why he turned down the role in what would become one of the biggest phenomenons of modern cinema.
When people reference bullet-time nowadays, most of us know exactly what that means and we instantly flash to Neo dodging bullets or Trinity (Carrie-Ann Moss) kicking someone across the room, but back in 1996, it may have been a tough concept to get across. As Will Smith explains in the video, although he recognized that the Wachowskis were brilliant, he couldn't understand exactly how this complicated visual-effects rig would work and decided to pass on the film. Instead, Smith made WILD WILD WEST, which was thankfully an enormous success and went on to spawn a lucrative multi-media franchise which is still thriving today. Yea, not exactly. "I'm not proud of it," Smith joked.
Looking back, Smith can recognize that he chose the wrong project, but he's glad that the role went to Keanu Reeves in the end because he was perfect for it. Smith also admitted that he "probably would have messed The Matrix up" and "ruined it" had he played Neo, so, you're welcome MATRIX fans.