I was just curious, because during the Supergirl arc in the old Jeph Loeb Superman/Batman series , Darkseid shows up at the Kent's house to attack Superman. So, I gather that this means that he knew that Clark was Superman. At the very least, he knows where he lives. Did he ever attack him at his house again after that? To my knowledge he has not, but if he does know who he really is or where he lives, do the math. Was his knowing his identity ever brought up again?

Speaking of villains who knew Superman's identity, who else knew? The only one that springs to mind is Manchester Black and the Parasite, but he died after. Mister Mxy also knew as well, but it's debatable if he's really a villain. He wouldn't do anything malicious with the secret. Did any other villain know? Couldn't Brainiac read his mind and figure it out? I also read that the Black Racer discovered his identity, when did that happen? Is there anyone that I'm missing? Thanks.