A guy who decides to be awesome when the right time comes. Members of the legion of Randomhero are the real past, present, and future.
Also, Randomhero's tend to be naturally gifted gamers.
Dude: That man is a champion
Other Dude: Naw man, he's a Randomhero.
Dude: He got the game yesterday, and he's already better than me, and I've had it for years
Other Dude: He's a Randomhero, what did you expect?