3. Circe
Yes, the witch from the Odyssey. However, shes also been used as a major villain for Wonder Woman, Circe being convinced that she will lose her magic powers to her, due to a prophecy. If the studio wanted to introduce Wonder Woman in the film, she could be seeking out Circe and the League could end up having a climatic fight with monsters from Greek myths that have been revived or re-created by magic.