Natsuo [Zero]

Pro Villain Absolute Zero - an AU of Natsuo Todoroki in which he ran away from his family home not long after Touya's death and developed along a similar but separate path to Dabi. He has no public connection to the Todoroki family and hides his face behind a featureless ice mask most of the time to hide his strong resemblance to Enji. He and Dabi also don't know about one another's identities (unless specific CR dictates otherwise), acting as (sometimes) friendly rivals in villain circles. Zero has no alignment or alliances, preferring to work alone.

He's known to be mysterious and unwilling to share much about himself with anyone, but can develop friendly relations in his own icy way given enough time. However, he's also highly volatile emotionally - all the fire in his family's bloodline seems to have gone into his temper - and stories of his rage very literally send a chill down the spines of even the most heartless villains. He's likely to have gone under the radar of more high-profile heroes due to his lack of alliances or particular cause, but those who work closer to street level could easily have heard of him as a sort of bogeyman, agent of chaos type, mythologized precisely because no one can get a handle on what he fights for or wants.

Y'know, because he can't either. He just knows he's alive, he's pissed off, his inner wounds have turned to rock-hard scars, and pure spite keeps him doing whatever it takes to sustain himself.