7 Reasons Why You Should Watch One-Punch Man
3. The Villains
The villains are the source of humor as much as the heroes, but they are also really impressively designed and drawn. In a more serious setting, they could actually be imposing and scary, but because we know the show is a comedy and One-Punch Man can't be beaten, they generally serve as objects of ridicule. No matter how big and chiseled they are, they'll eventually be beaten by this unimpressive bald guy.
Their origin stories are creative, but also over-the-top, which makes them all the more funny - especially when compared to Saitama's motivation for being a superhero. The villains are so pompous, unaware that their self-importance and self-confidence will quickly evaporate with just one punch by a regular-looking bald guy, that there's nothing left to do but just laugh at them.
Still, their destruction is often more serious than the overall tone of the series, and they serve as the sole instance of real threat, even though the outcome of their struggle is obvious from the start. Saitama may not find them imposing, but before he decides to show up, the villains are able to sometimes actually hurt a number of superheroes.