The CW's Arrowverse has been getting more and more ambitious when it comes to crossovers. After testing the waters with a few smaller attempts, they went in heavy with "Crisis on Earth X" and "Elseworlds," which brought all their shows together to battle a larger threat. But they really topped themselves with the 2019/2020 "Crisis on Infinite Earths" arc, which not only united the Arrowverse but gave us peeks into the BurtonVerse, the 1960s Batman world and even featured Ezra Miller cameoing as the DCEU Flash.