Casting movies is a tricky business. Get it right and a great story comes to life on the big screen, cinemagoers head home happy, Academy Awards are handed over, and the studio can confidently proceed with its sequel plans.
Get it wrong, however, and the film dies, franchise plans come tumbling down and the fans take up their metaphorical torches and pitchforks to stage a revolt that shakes the internet to its digital foundations.
There's so much riding on the lead actors. A top-class performance has the ability to mask poor scriptwriting or ham-fisted directing, but it simply doesn't work the other way around. No matter how sharp your screenplay is, regardless of who's sitting in the director's chair, bad acting or a miscast lead cannot be ignored.
The protagonist isn't just the face of the film, he or she is its heart and soul too, and if the audience isn't buying what they're selling, everything comes crashing down like a house of cards.
There are countless examples of poor casting decisions killing off films. Did anyone really accept Jake Gyllenhaal as Middle Eastern royalty in Prince of Persia, or Denise Richards as a nuclear physicist in The World Is Not Enough? Sadly, this trend isn't going anywhere since the amount of upcoming movies with the wrong actors on board is staggeringly high.
8. Rihanna - Ocean's Eight
Female-led spinoff Ocean's Eight is bound to cause controversy when it lands next summer. Just look at the stink the 2016 Ghostbusters kicked up when Sony boldly gender-swapped traditionally male roles.
Sadly for the Paul Feig-fronted reboot, it simply wasn't good enough to silence its critics, so the Ocean's Eleven spinoff will be in for a similarly rough ride unless it's something special.
The film's chances of success have been compromised somewhat by a weak link in the casting chain: Rihanna. She's a woman of many talents, sure - singing and dancing to name a few, but anyone who's sat through Battleship or Valerian & The City Of A Thousand Planets will tell you that acting isn't one of them.
The worst thing about this whole situation is that Ri-Ri will be starring in Ocean's Eight alongside some immensely skilled actresses - Cate Blanchett, Helena Bonham Carter, Anne Hathaway, Mindy Kaling, Sandra Bullock and Sarah Paulson - so her shortcomings will only be amplified by this stellar lineup.