The Mutant Leader

The Mutant Leader was the boss of the vicious mutant gang. His base of operations was the Gotham City dump. After Batman attacks the Mutants at their headquarters, he calls Batman a coward for using rubber bullets to mow down his followers rather than killing them and hiding in the batmobile. The Mutant Leader challenges Batman to a one-on-one fight, where he nearly kills the Dark Knight. He is about to impale Batman with a crowbar when Carrie Kelly (in her Robin costume) distracts him long enough for Batman to subdue him.

The Mutant Leader is arrested and brought to prison, but when the mayor tries to negotiate with him, the Leader murders him without second thought. Following a plan with Batman, Commissioner James Gordon deliberately releases him, and he finds the entire Mutant Gang assembled near a sewer outlet. Batman then ambushes him, leading to a bloody rematch. Despite his physical superiority, the Mutant Leader is no match for Batman's strategic mind; he chose the mudhole to slow the leader's movements, and he inflicts several major wounds. Eventually,  Batman overpowers the Mutant Leader, and the Mutants disband into smaller gangs.

The Lego Batman Movie
A LEGO version of The Mutant Leader appears in The Lego Batman Movie alongside other Batman villains.