There can be no argument about who Marvel's most badass assassin is. Deadpool is one of the most popular characters in the franchise, largely because of his humour, but his ruthlessness as a killing machine is completely unrivalled - perhaps throughout the history of comics. Deadpool is a trained military fighter than uses a combination of huge guns, katanas and a ridiculous fourth wall-smashing sense of humour to take out his targets. The Merc With A Mouth, as he's known in the contract killing trade, may not shut up while taking out his victims, but that doesn't stop him from getting the job done. Pit him against anyone else on this list and he'd more than likely destroy them without a second glance, especially given that his incredible self-healing powers render him practically immortal. Wade Wilson has one of the most impressive portfolios when it comes to victims too. This is the guy that took out almost every major figure in the Marvel universe in a single four issue run of comics. He killed all of the Fantastic Four, destroyed every member of The Avengers, wiped out the X-Men and killed the likes of Spider-Man, The Punisher and Ghost Rider. This is a guy with a serious hit-list. Given that Deadpool was effectively initially created as Marvel's mocking parody of DC's Deathstroke (whose real name is Slade Wilson... See what they did there?), it's impressive that he has grown into such an iconic and hilarious character on his own merits. It's also incredible that he has become the murderous and feared assassin in the whole of the Marvel universe.