Season 4

After a young circus performer named Dick Grayson loses his parents to a criminal named Tony Zucco, Bruce Wayne adopts the young boy. Once Bruce's secret is revealed, Dick joins Batman as his new sidekick, Robin. Together, they set out to find Zucco and bring him to justice.

After watching a movie about criminal masterminds, Penguin gets the idea to form a team of Gotham's greatest villains in order to finally take Batman down. Meanwhile, Batgirl and Robin must learn how to work together.

After the Joker's plan to make all the dogs laugh like hyenas is thwarted by Clayface (Ethan Bennett), he plans to prove himself to Batman by turning a new leaf. Meanwhile, actor Basil Karlo steals the mutagen responsible for Ethan Bennett for becoming Clayface and he becomes the new Clayface. Can Batman trust Ethan enough to help him stop Karlo?

When evidence from a series of art thefts by the Everywhere Man, a new costumed villain with the power to replicate, implicates Bruce's close friend John Marlowe, Batman believes there must be another explanation. Now, Batman must unmask the identity of the "Everywhere Man" and prove his friend's innocence.

After Batman apprehends Black Mask, his henchmen plan to spring him from Gotham P.D. so that Black Mask can activate his doomsday device. When Batman is captured, Batgirl and Robin must stop the villain on their own.

Hugo Strange infects the population of Gotham City with a virus that transforms them into zombies, and only Batman and Robin are left to find and distribute the antidote. But when Robin falls, only Batman can save the day. But not everything is at it seems ...

A thousand years into the future, the citizens of new Gotham must uncover the history of the Batman in order to stop a new Mr. Freeze.

The Bat Team goes up against an unstoppable thief who knows their every move.

The Riddler and Batman are dropped at the bottom of Gotham Harbor ... and the Riddler reveals his origins.

When Harleen Quinzell is cancelled from her television program, Joker takes an interest and decides to groom her as his new partner in crime, Harley Quinn.

The villains of Gotham City are disappearing, each one defeated and captured by an invisible vigilante named Rumor. Batman and Robin must defeat Rumor before he has a chance to execute the villains.

Bruce discovers that Wayne Industries is distributing alien technology across the world, and gains the aid of a mysterious new ally.

Martian Manhunter's prediction of an alien invasion by The Joining has come true. As Batman tries to stop them on his own, he learns that even working with a team will stop The Joining.