When the Challenge of the Super Friends season was originally conceived, it was named “Battle of the Superheroes” and featured the introduction of Captain Marvel to the Super Friends. The group that challenged the heroes was called the “League of Evil”, led by Marvel’s nemesis Doctor Sivana. However, Filmation produced Shazam! and The New Adventures of Batman which prevented the use of characters such as Mister Atom, King Kull, Beautia Sivana, Joker, Penguin, Mr. Freeze, and Catwoman. Early conceptual art drawn by Alex Toth would also include Heat Wave, Poison Ivy, and Abra Kadabra.
The Legion of Evil: Sivana, Sinestro, Captain Cold, Joker, Beautia Sivana, Penguin, Abra Kadabra, Poison Ivy, Heat Wave, Krull. Grodd, Mr. Atom.