Ellen Ripley was just one of many iconic female roles that almost never came to be
Off the back of Daniel Craig maybe/maybe not returning as 007, there's a landswell of popularity for the idea of a "Jane Bond" to take over.
Gillian Anderson, Emilia Clarke and Quantico star Priyanka Chopra have all publicly announced their desire to take on the role, but in the wake of the all-female Ghostbusters backlash, which can't be properly commented on until the movie comes out and we see the box office results, not to mention how people reacted to Idris Elba being a 'black Bond', we can only imagine the reaction to Jane Bond.
SIGOURNEY WEAVER in ALIEN
Originally intended for: N/A
Before we got to know Sigourney Weaver in the role that she was pretty much born to play, the part was originally written with a man in mind. But then director Ridley Scott had a brainwave moment, and decided to re-cast the role as female. Originally they had almost cast Meryl Streep in the part, but she dropped out when her boyfriend at the time died suddenly. Veronica Cartwright was then almost swapped into the role, but Scott put her back into the part of Lambert, and cast the then-unknown Weaver as Ripley, and the rest is movie history.
LEONARD NIMOY in STAR TREK
Originally intended for: Majel Barrett-Roddenberry
Back when the show was just kicking off, the second-in-command on the Starship Enterprise was known as Number One, and had originally been cast as Gene Roddenberry's second wife... except at the time she hadn't yet become Mrs Roddenberry, and was his mistress at the time. Producers of the show got cold-feet about the whole situation, and Nimoy was inserted into the show as their "logical" choice, and Barrett was recast as Nurse Chapel.
JODIE FOSTER in FLIGHTPLAN
Originally intended for: Sean Penn
The Hitchcock-lite tale of a missing child on an transatlantic flight certainly doesn't seem like an easy fit for Sean Penn, but when you hear that the original script was also full of terrorists and sounded like a Die Hard movie, it makes even less sense. Coincidentally, years earlier, Foster was due to play the troubled sibling of Michael Douglas in David Fincher's The Game, but she dropped out and was ultimately replaced by ... Sean Penn!
ANGELINA JOLIE in SALT
Originally intended for: Tom Cruise
Edwin A. Salt was almost a go, before Cruise got a bit concerned that the spy character would be too similar to his Mission: Impossible franchise, and decided to drop out and do the forgettable Cameron Diaz co-starrer Knight & Day instead. So in steps Jolie, and the script was barely changed at all, except know she was known as Evelyn Salt, and actually rewrote it so she didn't have kids in it, instead of the usual trope of "She's a lady, here's a family" that Hollywood can be guilty of giving their female stars.
SLAVITZA JOVAN in GHOSTBUSTERS
Originally intended for: Pee Wee Herman
There were a lot of changes made to the Ghostbusters cast leading up to the movie. John Belushi's role went to Dan Aykroyd, Eddie Murphy was originally intended for the part that went to Ernie Hudson, and John Candy was supposed to be the annoying neighbour, not Rick Moranis. However, its Yugoslavian model Slavitza Jovan that caused the biggest change, as the big bad guy/gal Gozer was envisioned as an unremarkable slender man in a suit, set to be played by Paul "Pee Wee Herman" Reubens. So there you have it, Ghostbusters has been swapping gender roles since it began!
SANDRA BULLOCK in OUR BRAND IS CRISIS
Originally intended for: George Clooney
Having previously worked together on a movie where they were both last-minute replacements - Gravity had Angelina Jolie and Robert Downey Jnr. as the stranded astronauts initially - Bullock put the feelers out for any scripts intended for men that could be reworked in her favour, and Clooney, who remained on board as a producer, flagged this project. Which, considering how it worked out, wasn't much of a favour at all, really.
MARK HAMILL in STAR WARS: A NEW HOPE
Originally intended for: N/A
Early drafts of Luke Skywalker had him as a female character named Starkiller (which producers at Fox didn't care for much because it sounded a bit too dark for something they wanted to put on toys), but considering Han Solo was a man-sized lizard and Yoda was a massive giant, it's fair to say that the script made a fair few changes before it hit the screen.
GWENDOLINE CHRISTIE in STAR WARS: THE FORCE AWAKENS
Originally intended for: Benedict Cumberbatch
And now here we are, all these years later, and Star Wars is still switching things up. While the Cumberbatch casting actually never made it passed the rumour-mill, it was confirmed that Captain Phasma was originally intended for a man, but in light of the initial cast-photo, it was seen as being pretty male-heavy. In balance that out, Phasma was rejigged to being a female, and Game Of Thrones' resident bad-ass kick-ass was cast.