The Outsider is a supervillain from DC Comics who was originally an enemy of Batman, but a later incarnation of the character would also become an adversary of the Justice League.
On Earth-One, while his employer Bruce Wayne was out of town, Alfred Pennyworth learnt of a criminal group that Bruce (as Batman) was monitoring and decided to personally track them down. However, Alfred was captured and used as bait to lure Batman and Robin straight into a trap. The Dynamic Duo soon arrived to save Alfred, but the butler instead sacrifices himself to save the heroes by walking into the trap before them. Although it was believed that he was killed, Alfred actually managed to survive but was on the brink of death. He was discovered by a physicist named Brandon Crawford who used a special radiation treatment that not only saved Alfred's life, but also transformed him into a powerful supervillain called The Outsider.
Fueled by his hatred for Batman, The Outsider sent various criminals to kill the Dark Knight and made a couple of his own attempts before Batman learnt of the villain's true identity and manages to restore Alfred to normal. However, The Outsider persona would eventually resurface after Alfred receives an nasty blow to the head. The Outsider would this time focus his efforts on Batman's allies by founding the Sunset Gang to eliminate Man-Bat, but to no prevail. Tired of his failures, The Outsider made a final attempt to take the lives of Man-Bat, Robin and Batgirl. But overconfidence in his plan proved to be his downfall, as he failed to realise the three were working together to stop him. An incident accidentally causes The Outsider to be separated from to body of Alfred Pennyworth, which deprives him of his powers, and he was easily defeated by the heroes before being vanquished for good by Alfred.
In this continuity, The Outsider is a villainous version of Alfred Pennyworth from Earth 3, who assisted Thomas Wayne Jr. in murdering his parents for their fortune. Alfred continued to assist Thomas years later during his activities as Owlman, although this made him a target for the Joker (of Earth 3) who exposed him to a dose of Joker Toxin that permanently turned his skin chalk white and occasionally causes him to have fits of laughter. When Earth 3 was destroyed by the Anti-Monitor, surviving members of the Crime Syndicate sent Alfred to Prime Earth in search for Pandora's Box, which was actually a device that can open a gateway between universes. The Justice League fought against The Outsider's forces to stop him, but he manages to obtain the box and uses it to send the Crime Syndicate to Prime Earth so they conquer it for themselves. Alfred continued to aid the Syndicate in their plans until was killed by Black Manta during a raid.