One Punch Man is a series that stands out mostly for its comedy, but everything surrounding Saitama, the main character, is something that gets a lot of interesting discussion. The protagonist's overwhelming strength, coupled with his simple yet fascinating personality, has made him extremely likable, although much about his life, including his full name, is not known.
Throughout the vast majority of the One Punch Man series, the protagonist is simply known as Saitama or Caped Baldy, which is his hero name. So a lot of people in the fandom have begun to wonder if he has a full name or if he is only known as Saitama, which is a small detail that can give more characterization to the protagonist.
Disclaimer: This article contains spoilers for the One Punch Man series.
Saitama does not have a full name in the One Punch Man series
In short, Saitama doesn't have a full name as it is never shown throughout the One Punch Man series. This is further emphasized when the character begins to join the Hero Association and there are no details about his background or his full name, which are required to become a part of this organization, which is a clear giveaway.
Furthermore, as Saitama's exploits begin to become a lot more prominent and characters like Flashy Flash or Bang start to show an interest in him, his full name is never revealed.
It is also worth pointing out that this isn't a huge mystery in the series or something along those lines but rather just a little detail that shows that that particular aspect of the character's identity is not important.
The reason ONE, the author of the series, doesn't give Saitama a full name can be down to a lot of different reasons but is most likely due to adding more comedic elements to the story.
Making the most powerful character of his entire universe just go by the name of Saitama can add to the irony of the story and all these little elements are what makes One Punch Man such an appealing series.
The appeal of Saitama in the series
It's easy to look at the character of Saitama and think that he is far too powerful for the story, constantly defeating every single enemy out there with a single punch, no matter how strong they are. That's the entire point of the story, although is also worth pointing out that Saitama is very important for the series, mostly for reasons that go beyond his role as the protagonist.
Saitama's journey across the One Punch Man series is an example of the "flat character arc" in fiction, which is having a protagonist who doesn't change quite a lot but rather changes the world around him.
This is quite clear through Saitama's actions, changing and influencing characters like Genos, Fubuki, Garou, and many more while also having a significant impact when fighting the villains.
Of course, there is also the fact that Saitama himself is a metaphor for what happens when a person reaches the peak of a certain discipline and doesn't have any challenges anymore.
Saitama goes about his day without any challenges or anything that can test his limits, which is often used as a joke but also explores what happens when a character can't go further beyond.
Final thoughts
Saitama doesn't have a full name in the One Punch Man series and it has never been shown across the entirety of the series. There has never been given a reason about why the character doesn't have a full name, but is probably done for comedic reasons.