No list about single hit victories would be complete without a One-Punch Man (AKA Saitama) inclusion. The character makes a habit of finishing off his opponents in a single blow - it's his schtick (can you tell by his name?) - but this particular instance in "Because It's Raining" (Chapter 27, Volume 5 of the One-Punch Man manga) has to be one of the most impressive. The powerful Sea King had just demolished an office building in his weaker form and had easily defeated two other very powerful heroes in physical combat - but then he came up against the titular hero. Even in his true, more powerful form, the Sea King had no chance against Saitama. The villain threw a punch at the titular character, but a retaliation from him didn't just knock him out, it killed him - blowing a massive hole in his body.
