Sexual chemistry: you either got it or you don't. Film, of course, is awash with screen couples who look completely uncomfortable together and obviously have no connection whatsoever. Quite worryingly, this was certainly the case with married couples Ben Affleck and Jennifer Lopez in Gigli and Tom Cruise and Nicole Kidman in Eyes Wide Shut. Needless to say, those relationships didn't limp on for a great deal longer... But there have been some screen pairings whose chemistry sizzled so hard that they were capable of sending the audience into a total meltdown. Some of the duos listed here were already public items, some were are already cosying up in secret, whilst others weren't even attracted to the same sex as their co-star. Some even disliked each other intensely in real life, making their performances together even more remarkable, whilst one couple had never met before filming, and never hung out again afterwards, but spent their short time together burning up the screen. I could write an article about 100 such screen couples and still quite conceivably miss your favourites out, so feel free to add your own suggestions in the comments section below (as long as it's not Robert Pattinson and Kristen Stewart - hours of gormless staring does not mean chemistry). Spoilers within, of course.