One-Punch Man (anime)

A 2015 anime about a bald guy, based on the manga who is based on a webcomic of same names.

Saitama is just a hero doing his hero job. The thing is, things are easy. Very easy. And that's because Saitama is powerful. Very powerful. To be more exact, almost 99% of his enemies go down in one punch. One. Punch. That's all thanks to Saitama's training, that apparently also made him bald. Thing is, Saitama has become so powerful and his job has become so easy, that he is becoming bored of the superhero business. Such a pity, because now is when both heroes and superpowerful monsters are finally noticing his existence.

The truth is, One-Punch Man isn't a serious story. It's a comedy and a parody of both superhero comics and fighting manga.

The first season was directed by Shingo Natsume and animated by Madhouse. The second one was directed by Chikara Sakurai and animated by JC Staff. Based on a Seinen manga with art by Yusuke Murata, adapted from a webcomic written and drawn by ONE.

Tropes used in One-Punch Man (anime) include:

Anti-Hero: Puri-Puri, first appearing on Episode 7, is one of a category hard to define: despite the fact he is an homossexual rapist, he is still wants the better for society and fights villains as a hero. He seems unrepentant of his sexual violence as he seems honest in trying to defend innocent people of villains.
Arbitrary Skepticism: Everyone finds Saitama's training regime results absurd despite the fact pretty unrealistic technology and magic exist in the series' setting.
Blood Knight: Sonic immediately turns into this at seeing Saitama survive his assassination attempt, wanting him dead at any cost.
Book Ends: In Episode 4, Hammerhead is seemingly killed two times by a strike in the head but runs away, thanks to inherent toughness he have on that part of the body.
Cute Monster Girl: The Mosquito Girl from Episode 2 is way more humanoid and sexy than her male counterparts of the House of Evolution.
Cyborg: Genus and Armored Gorilla, one human and the other, well, obviously a gorilla.
Dark and Troubled Past: Parodied. Genos' backstory in Episode 2 is presented through voice-only narration which goes on for a long period of time, annoying both Saitama and presumably the villain.
Dirty Communist: Hammerhead is a exaggerated parody of the trope. He wants everybody to not work unless they want to, and is willingly to use lethal violence to accomplish.
Fanservice Extra: For all of her hotness, Mosquito Girl doesn't last even one entire episode before Saitama easily kills her with an slap.
For Science!: Dr. Genus' experiments were created with the objective of vastly improving the human race with super-powers related to other animals. He lets them roam free but has no plans of domination or profit.
The Greatest Story Never Told: Discussed and defied. Saitama becomes pretty bothered for not being known by Episode 4 after saving so many people but yet still be mistaken for a villain, and in the end decides to enter the Hero Association to get some, if any fame.
Groin Attack: Episode 4. Saitama inadvertently punches Sonic in the groin when he had just wanted to scare him of attacking.
Lonely at the Top: There is no doubt Genus is a genius, even if it took decades for his hybrid experiments to give fruit. It also made him isolated from other people to the point the entire staff of the House of Evolution are his own clones.
One-Hit Kill: Unless they're on a pretty high scale of power, monsters and villains die to Saitama from one punch.
Power Parasite: The best way of explaining Mosquito Girl's powers, given feeding on large quantities of blood should make her fast, not change her color and make her vastly more strong and durable.
Punch Clock Hero: Sonic is first seen fighting the decidedly villainous faction of Hammerhead, but he is only doing it because he was paid to by a rich businessman. He attacks Saitama completely unprovoked just because he grabbed his projectiles, and showed no concern in possibly killing an innocent man.
Something Something Leonard Bernstein: The theme song is mostly in Japanese but has a little English.
Super Speed: Speed-O-Sonic's main power is being able to move in incredible speed. Sadly for him, Saitama is also able to do it and it has incredible strength to completely outmatch him.
Training from Hell: Saitama's training regime which he said that managed to turn him invincible would be pretty brutal even to trained iron-men, something given the popularity of the series was analyzed by actual fitness trainers and deemed feasible but pretty hard to do. Of course, it doesn't result in hyper-speed and strength and toughness.
Too Dumb To Live: A thief gets killed in Episode 2 by a horde of mosquitoes by ignoring the warnings about monsters attacking just to get more gold.