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In page Penguin (character):

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The idea of the Penguin and the Joker as a team is one that is decades old, as the two villains, pop-culture wise, are arguably Batman's two most famous enemies. Their first meeting took place fairly early, in "Knights of Knavery".[1] Since then, the two have teamed up countless times throughout the Golden and Silver Ages. This carried over into television as well; both appeared together as a team numerous times. They have even shown affection towards each other on more than one occasion; in one story, the Joker actually cries when it appears that the Penguin has been murdered, and vows to avenge the Penguin's death.[2]