Heroes (ヒーロー, Hīrō) are individuals who fight for justice against all evil in the world. They also protect innocent civilians from any harm against natural disasters, Mysterious Beings, and Villains. Most heroes are registered with the Hero Association and are divided into four classes: C-Class, B-Class, A-Class and S-Class, each having their own individual numbered rankings within the class. However, the Rank 1 heroes of A, B, and C classes are substantially more powerful than the bottom-ranked hero of the next class up; they chose to keep their Rank 1 position in their current class as a gatekeeper for reasons of their own.
To see a list of all unnamed heroes, see List of unnamed heroes.
To see all characters, see Characters.
To see all characters that appeared in the webcomic, see Characters - Webcomic.
S-Class (S級, S-kyū): The highest class in the Hero Association. Here gather the most powerful heroes, who are said to be insanely strong, at least as much as an emergency army division. This class was originally created to gather individuals who, despite their low ranking, were capable of defeating Disaster Level Demon Mysterious Beings on their own. The currently highest-ranked S-Class hero is Blast. There are currently 17 heroes in this class. S-Class has the smallest number of heroes out of the four classes.
A-Class (A級, A-kyū): is the second strongest class out of the four classes. When a hero reaches Rank 1 of B-Class, he/she can climb up to A-Class. Heroes in this class are considered very powerful and are often the most popular heroes. The currently highest-ranked A-Class hero is Sweet Mask. There are currently 38 heroes in this class.
B-Class (B級, B-kyū): is the second weakest class. When a hero becomes Rank 1 in C-Class, he or she can climb up to B-Class. Heroes in this class are stronger than the previous rank and do not have to perform weekly heroic acts to fulfill any quotas. The currently highest-ranked B-Class hero is Fubuki. There are currently 101 heroes in this class.
C-Class (C級, C-kyū): is the lowest class out of the four classes. Although C-Class heroes are the weakest, their strength exceeds that of an average person in usually. When a hero enters the association, he/she begins here (unless they score high enough on the exam, in which case they can directly climb up to a different rank). C-Class heroes must perform weekly heroic acts to fulfill their quotas, otherwise they are removed from the Hero Registry. The currently highest-ranked C-Class hero is Mumen Rider. There are currently about 390 heroes in this class. C-Class has the most heroes out of all the classes.
Unknown Class: Heroes whose Class and Rank are unknown.
- Murata would be a C-rank hero called Sakuga Nebukuro, who only collapses when he sleeps. While he sleeps he draws pictures. ONE would be a C-rank hero called Trash collecting man who collects trash.
- Genos is the first S class hero in 2 years  however this is contradicted in Weapon where Metal Bat is promoted to S-Class one year ago.