Paul Graham. Isn't it common knowledge that this is his site? I mean, I suppose that legally, it's Y Combinator's, but PG wrote it and has always run it.

I doubt he has the time to read every flagged message. That's why I was asking about what is the hellbanning process, if several people are involved.

You can be hellbanned manually by a moderator (PG is the only moderator whose name is publicly known AFAIK, but there are others) or automatically by the system for going severely negative in karma.

He has other mods too.

Yes, but the question included 'ultimately', which would refer to PG in this case.