Bizarro is a villainous character from DC Comics. He is an imperfect clone of Superman, characterized by his opposite personality, mannerisms, even some of his powers. There have actually been multiple Bizarros within the DC Comics universe, each with their own origins and have acted as either an enemy or ally to Superman depending on the situation.
Bizarro-Clark (Smallville)[]
The Smallville incarnation of Bizarro (portrayed by Tom Welling) was originally a malicious entity that had escaped from the Phantom Zone. It attempted to possess a number of human hosts, only for each of them to die as human physiology could not cope with the entity's presence. At the end of Season Six, the phantom came into contact with Clark Kent, but rather than possessing him, it was able to assimilate his DNA and form a body for itself, gaining all of Clark's abilities in the process.
As soon as "Bizarro-Clark" came into being, its main focus was survival. From the memories it had absorbed from the real Clark, it sought out Lex Luthor in order to gain his assistance in killing Clark. The clone discovered that it became more powerful after absorbing radiation from green kryptonite and Lex took the clone to his ruined lab at Reeves Dam to obtain more. However, Lex double-crosses Bizarro and the clone knocks him out.
The real Clark then arrives and a showdown ensues between him and his doppelganger. Bizarro becomes stronger after absorbing the kryptonite radiation and lays Clark out, but the rays of the sun heal Clark in short order. Bizarro, on the other hand, is weakened by the sun's rays and his face becomes distorted. Clark charges at Bizarro and uppercuts him into the stratosphere where he is captured by J'onn J'onnz and imprisoned on Mars.
Months later, Bizarro escapes from Mars and returns to Earth where he is able to easily take over Clark's life since, at the time, Clark was being held prisoner in the Fortress of Solitude. He told Lana Lang that he wanted to help take Lex down and Lana revealed to him her lab at the Isis Foundation where she was attempting to care for Casey Brock, who had been poisoned by Brainiac. Bizarro recognized that Brock was speaking Kryptonian and sought out Chloe Sullivan's help to translate it, coincidentally saving her and Jimmy Olsen from an explosive device. Together, they learned that Brainiac was attempting to reboot itself.
Bizarro tracked down Brainiac to ask him for a way to live under the sun and take Clark's place permanently. Brainiac was too weak to help him, but divulged that a Kryptonian scientist named Dax-Ur, who could be located with a shield, could help. Bizarro went to the Fortress of Solitude to look for the shield and alerted Jor-El to his presence, which led to Clark being freed from his icy imprisonment to put a stop to his lookalike's plan. Bizarro again asked Chloe for help, but his behaviour made her question if he was really Clark: she was proven correct when Clark returned. Lana was also informed of Bizarro's charade and was shocked to realize that she had been living with an impostor for over a month.
However, Brainiac was using both Bizarro and Clark to locate Dax-Ur for himself. While posing as Lionel Luthor, Brainiac told Clark that he could acquire a supply of blue kryptonite from Dax-Ur and use it to destroy Bizarro. Meanwhile, Bizarro followed Lana to Oliver Queen's apartment and Lana called Clark for help when she saw Bizarro's true appearance in the sunlight. Clark arrived, but was powerless once he opened the lead box containing the blue kryptonite: as such, he was left unable to get close enough to Bizarro to defeat him. Finally, Lana declared her love for Bizarro, who lowered his guard long enough for her to place the blue kryptonite in his hand. Shortly before exploding, Bizarro then reciprocated Lana's feelings. His last words were "I love you".