There are several characters in the One Punch Man universe who are aware of the true strength of Saitama, the protagonist of the series. These characters have either witnessed his power firsthand or have been informed about it by others. However, it's important to note that Saitama's true strength is often heavily underestimated or dismissed due to his unassuming appearance. Here are some of the characters who know or have an idea about Saitama's power: 1. Genos: Saitama's disciple and close companion, Genos has witnessed Saitama's devastating power multiple times. He has fought alongside Saitama and has seen him effortlessly defeat powerful opponents with a single punch. Genos is one of the few characters who truly understands just how strong Saitama is. 2. Bang (Silver Fang): Bang witnessed Saitama's power during the Hero Association's fight against the Monster Association. While initially skeptical of his abilities, Bang witnessed Saitama effortlessly destroy countless monsters, including a dragon-level threat. This encounter made Bang deeply respect Saitama's true power. 3. Flashy Flash: After engaging in a brief fight against Saitama during a battle between the S-Class heroes and the Monster Association, Flashy Flash realized that Saitama's speed, strength, and reflexes are on a completely different level. Flashy Flash was left in awe and acknowledged Saitama's incredible abilities. 4. King: Although King himself is aware that he is not truly powerful, many characters, including some S-Class heroes, believe him to be the strongest hero in the association. Saitama's true strength is accidentally witnessed by King on multiple occasions, creating a humorous dynamic between the two. King recognizes that Saitama's power is far beyond his imagination. As for how Starcraft characters might react to Saitama, it's difficult to say as they belong to different fictional universes. However, given the overwhelming power and speed demonstrated by Saitama, it is highly likely that most Starcraft characters would be astounded and view him as an unstoppable force. The magnitude of Saitama's power would likely surpass anything they have encountered in their own universe.

In a crossover scenario between Starcraft and One Punch Man, the characters from the Starcraft universe would have varying levels of knowledge and understanding regarding Saitama's true strength. It's important to remember that the comedic nature of One Punch Man often plays with the idea that Saitama's power is vastly underestimated or dismissed due to his unassuming appearance. Here are some Starcraft characters who might be aware or have an idea about Saitama's power: 1. Tychus Findlay: Tychus is a hardened marine and one of the main characters in the Starcraft II campaign. He possesses immense strength and is known for his bold and brash personality. If Tychus ever encountered Saitama and witnessed his power, he would likely be impressed and might even compare Saitama's strength to his own. 2. Zeratul: Zeratul is a Protoss Dark Templar who possesses exceptional combat skills and deep knowledge of the cosmos. If Zeratul were to meet Saitama, he might sense his latent power through his psychic abilities. Zeratul's reaction would likely be one of intrigue and curiosity, as he seeks out strong allies and worthy opponents. 3. Kerrigan: As the former Queen of Blades and one of the most powerful characters in the Starcraft universe, Kerrigan has gained immense strength and psionic abilities. If Kerrigan were to encounter Saitama, her initial reaction might be one of skepticism, as she would likely assume his power to be exaggerated. However, if she witnessed Saitama's true strength, she would quickly realize the immense power he possesses and might even try to recruit him for her cause. 4. Jim Raynor: As the main protagonist of the Starcraft series, Jim Raynor is a skilled soldier and leader. If Raynor were to encounter Saitama, he might not fully grasp the extent of his power at first. However, after witnessing Saitama's strength in action, Raynor would likely be left in awe and recognize him as an incredible ally in their struggle against the Zerg or other threats. Ultimately, the reactions of Starcraft characters to Saitama's power would vary. Some might be astonished and view him as an unstoppable force, while others may take a more measured approach. However, Saitama's overwhelming strength would likely impress and amaze most, as they have never encountered someone with such raw power in their own universe.