I'm gunna say Zeus, because I remember him being uniquely terrible.
What I'm getting from these anime answers is that the dads tend to be over the top awful, but in ways that aren't very nuanced or clever. It's like if someone wrote a story of, I don't know, a father figure kept torturing their son to death for eternity and bringing them back to life once they died to relive it.
It's not hard to just be over the top terrible and say "for eternity" as a stinger, so I assume there's like a billion such characters in short stories or whatever. At some point, it feels like it's less about them uniquely being a dad, and it moreso the case that they just happened to be related to them prior to eternity torture or whatever.
It's way harder to inflict the sort of mental damage Jonas did, since that's contingent on writing quality and a far longer arc.