One-Punch Man delights in parodying and referencing other anime series and stereotypical genre tropes, and here are the most notable examples. Bursting onto screens in 2015, One-Punch Man was touted as a refreshing take on the battle anime genre, mixing genuine high-octane action with hilarious gags and riffs on other popular franchises. As Saitama's story has progressed, the more serious elements have arguably become more pronounced, but ONE and Yusuke Murata's manga and the resulting anime adaptation still make time to rib their contemporaries.
While some of the references are overt visual gags, others take thematic cues from other famous anime properties. However, One-Punch Man is perhaps better described as deriving humor from the cliches of Shonen-style manga, deliberately subverting the genre and fans' expectations. With some of the best examples of this coming early in One-Punch Man's debut season, it could certainly be argued that this element played a large part in the early popularity the series enjoyed.
Dragon Ball
There are two major Dragon Ball parodies in One-Punch Man, the first of which comes in virtually the first scene, firmly setting the tone for things to come. The first villain viewers see Saitama take down is Vaccine Man, who Dragon Ball fans will immediately recognize as a blue version of Piccolo. With the same sharp facial features, head antennae and muscular physique, Vaccine Man is a dead ringer for the Namekian and, interestingly, both characters share the same English voice actor. Vaccine Man's origin is also a parody of Baikinman, the germ-based baddie from Anpanman.
In One-Punch Man season 2, Saitama takes part in the Super Fight martial arts tournament, which feels like a deliberate play on the World Martial Arts Tournament arcs that were a key part of the Dragon Ball franchise. One-Punch Man even follows the same story structure, showcasing individual bouts, with the tournament's finale ruined by the arrival of a major new villain.
Some viewers have speculated that Boros, the final villain of One-Punch Man season 1, is partially inspired by the Super Saiyan trope, with the villain simultaneously increasing in strength and hair definition as his fight with Saitama progresses.
Attack On Titan
In addition to Vaccine Man, another monster in One-Punch Man's opening episode acts as a parody of a rival series. Thanks to his scientist brother, Marugori is transformed into a super strong giant that terrorizes multiple cities, trampling them under his feet. With a sinewy body and hardened white skull, Marugori is a clear nod to the Colossal Titan in Attack on Titan, which One-Punch Man hilariously makes light of by having the giant accidentally squash his brother instead of Saitama.
Similarly to Vaccine Man, the English voice actor for Marugori is actually the same as Attack on Titan's Eren Jeager, providing a further connection between the two series that may or may not be coincidental.
Naruto
While the S-Class hero Flashy Flash has yet to feature heavily in the One-Punch Man anime series, his backstory and abilities have been explored in the manga and bear a striking resemblance to Masashi Kishimoto's Naruto. Like the ramen-loving Hokage, Flash is a ninja who graduated from a mysterious hidden ninja village. Some of Flash's elemental techniques also wouldn't look out of place in Naruto's world. Turning the parallel on its head, however, the ninja village in One-Punch Man is revealed as a torturous place that keeps children captive, perhaps commenting on Naruto's use of children as mercenaries. Flash is notorious for massacring his fellow villagers, which could be a reference to Itachi Uchiha's arc in Naruto.
Other Anime Series Parodied By One-Punch Man
One-Punch Man's resident martial arts master, Silver Fang, is a close physical match for Zeno Zoldyck in Hunter X Hunter, and the fact that both characters are masters of their respective art forms and have outlandish facial hair only solidifies the connection. In One-Punch Man's first season, Saitama and Genos come up against a transforming villain known as Carnage Kabuto who, upon entering his final "Carnage" form, is immediately reminiscent of Eva Unit 1 from Neon Genesis Evangelion, right down to the purple and green color scheme and massive horn.
One-Punch Man Season 3 is currently without a release date. More news as it arrives.