I never considered Lucifer showing up, since his show isn't really superhero-y. That said, as someone who enjoys that show, I really hope he does show up (and he needs to at least exchange some dialog with Constantine).
I also really hope that Knox form the 89 Batman movie shows up, that would be a neat cameo.
Well, when it comes to other Lex Luthors, Clancy brown has appeared in the Arrowverse before (as general Eiling). Just get him a bald cap, and he wouldn't be an out of place older Lex. Since we're already getting Kevin Conroy as Bruce Wayne its not impossible, especially since we know that Rosenbaum isn't showing up.
I also really hope that Knox form the 89 Batman movie shows up, that would be a neat cameo.
What I find interesting about the whiteboard, though I could be misinterpreting:
It seems to be a list of distinct characters, including three Supermen and two Loises... and it looks like two Lexes as well. So far only Cryer's Lex has been confirmed to appear. So that might imply there will be another.
Well, when it comes to other Lex Luthors, Clancy brown has appeared in the Arrowverse before (as general Eiling). Just get him a bald cap, and he wouldn't be an out of place older Lex. Since we're already getting Kevin Conroy as Bruce Wayne its not impossible, especially since we know that Rosenbaum isn't showing up.