Traditionally, historians don't like to play "what if" with history. You can't change the past, so better to focus on what did happen, not what could have happened. Of course, while history majors were getting their PhD's, the rest of us were hanging around our dorms, wondering what it'd be like if some of our favorite films had went with their original leading men.

American Psycho
(Leonardo DiCaprio as Patrick Bateman)
Shortly after its publication in 1991, Bret Easton Ellis's notoriously violent 1991 novel was deemed "unfilmable." Of course in movie parlance "unfilmable" is shorthand for "unfilmable until sufficient hype is built up," and 10 years of rumors and unproduced scripts followed — including talk of Johnny Depp in the lead role. But it was Leonardo DiCaprio who came closest to filling Patrick Bateman's blood-splattered tennis shoes when Lions Gate Films officially announced DiCaprio was cast as the film's lead. Fortunately, DiCaprio soon realized the hordes of 13-year-old girls who fell in love with him in Titanic may not be best served by seeing their idol chase a terrified hooker with a chainsaw, and the role went to Christan Bale.

The Terminator
(OJ Simpson as The Terminator)
In 1994, OJ Simpson super-saturated all forms of media. Imagine how much worse it would have been if the alleged murderer was most famous for playing a killer future-cyborg. While a generation of late-night comedy writers and NY Post editors may mourn the missed opportunities,the rest of us can breath a collective sigh of relief that, ironically,director James Cameron thought the former running back was too much ofa "nice guy" to play his murderous robot. (In another near miss,Cameron failed to get Billy Idol for the liquid metal killer in T2,precluding the possibility of a Skynet into punk rock chic.)

Lord of the Rings
(Stuart Townsend as Aragorn)
After only four days of shooting, producers fired Stuart Townshend for being "too young", which is probably movie code for being "too much of an insufferable sissy boy". It was a smart move – alongside a prepubescent hobbit, a clownish dwarf, and an elf portrayed by fresh-faced British actress Orlando Bloom, Viggo Mortensen provided some much-needed testosterone. While Townshend spent his days in an air-conditioned trailer, Viggo reportedly went so far as to live like Aragorn, hunting his own food, making his own clothes, and slaughtering marauding orcs whenever they would wander through set. (To the families of those cast members and stunt men, we offer our condolences.)

The Matrix
(Will Smith as Neo)
Hancock as our post-apocalyptic savior? Oh hell naw. Will Smith was offered the the chance to learn kung fu, but turned it down to appear in the unmitigated disaster Wild Wild West. Missing out on one of the all-time best summer movies to appear in one of the all-time worst would get most people down, but Will Smith is apparently as cheerful and positive as his rapping would lead you to believe. In an interview with Wired he commented, "I would have absolutely messed up 'The Matrix.' At that point I wasn't smart enough as an actor to let the movie be — whereas Keanu was." It's hard to guess what Will Smith regrets more – not being in the first Matrix, or his wife's participation in the sequels.

Back to the Future
(Eric Stoltz as Marty McFly)
The story goes that Michael J. Fox was always the first choice to play Marty McFly, but couldn't due to his commitment to Family Ties (oldest excuse in the book). The producers got as far as shooting 3 million dollars worth of time travelling mayhem with Eric Stoltz, but felt he wasn't right for the part. The producers of Family Ties and Back to the Future got together – presumably over fancy cigars and brandy – and were able to work out a deal where Michael J. Fox just didn't get to sleep for a few months. But maybe, just maybe, the directors actually completed the movie with Eric Stoltz, and he became a big star. Michael J. Fox, bitter that he missed the role of a lifetime, used his Family Ties money to build a time machine, went back, and changed the past. That's an altered history even Doc Brown could be comfortable with.

Star Wars
(Kurt Russell as Han Solo)
The story of how a humble carpenter named Harrison Ford was pulled from the workshop by George Lucas and became Han Solo has become the stuff of Hollywood legend. In reality, Ford followed dozens of up-and-coming actors who lobbied to pilot the Millennium Falcon, among them Nick Notle (too grizzly), John Travolta (not grizzly enough) and Richard Dreyfuss (voice sounded too much like C-3P0). Kurt Russell was also among the Solo hopefuls, but despite the scruffy, Solo-like charm he would later demonstrate in Used Cars and Overboard, it wasn't to be. Tragic, though it gave Russell the freedom to play a one-eyed mercenary named Snake Plissken in Escape From New York, which is worth 10 Han Solos.

Raiders of the Lost Ark
(Tom Selleck as Indiana Jones)
Have you ever watched Raiders of the Lost Ark and found yourself wondering, Gee, Indiana Jones could really use a mustache. Didn't think so. Nevertheless, that's what audiences would've been treated to had George Lucas and Steven Spielberg landed Tom Selleck, he of the perpetually hairy upper lip, who was the producers' first choice to play Indiana Jones. Selleck had already won the role, but was forced to pass in order to honor his contract with Magnum P.I. Of course, there's always the possibility that, had he played Dr. Jones, Selleck would've shaved his mustache, but we're sure we speak for all Selleck aficionados when we say nobody wants that.

Additional writing by Ben Joseph.