Along for the ride will be Burt Ward (who played Robin in the original Batman series), legendary Batman / Bruce Wayne voice actor Kevin Conroy (who’s never played the character in live action until now), at least two versions of Superman (add Tom Welling, please!) and some of the heroes from Black Lightning (previously unconnected to the Arrow-verse even though it’s another DC show) are also confirmed to appear.
There will also be fancy-pants guest stars aplenty in the crossover episodes, with many giving us visions of DC heroes past, or versions of some popular characters who’ve never been in live action before.