I mean, it was initially confusing to learn that Joaquin Phoenix would star in a solo movie about The Joker instead of the current live action Clown Prince of Crime at the time, Jared Leto, until they specified it was an “Elseworlds” origin story, of sorts. Speaking of Joker, there are actually a few possible references in the Oscar-winning film to the DC villain Ratcatcher, who will also be featured in the DCEU continuity, but in an entirely new iteration. Plus, we could talk for hours about how Carla Gugino was meant to play Catwoman in Batman v Superman: Dawn of Justice before that plot detail was scrapped, or the many actresses considered for the same role in Gotham City Sirens before they released Birds of Prey instead. Hmmm…
Article source: https://www.cinemablend.com/news/2559086/all-the-batman-villains-who-exist-in-the-dceu