Uncle King Julien XII is the main antagonist of his nephew's own story, the hidden main antagonist of All Hail King Julien and the secondary antagonist of All Hail King Julien: Exiled. He is is rude, dishonest, obnoxious, evil, lazy, sarcastic, deceiving, selfish, vain, cowardly and idiotic.
Towards the end of the series, Uncle gives up on taking the throne back, because he fell in love with Zora and wanted them to run away together. Julien pardons them both and allows them to marry and live a happy life toghther. This explains why he didn't try to take the throne back from Julien when he, Maurice, and Mort left Madagascar for good in the second movie.
Uncle King Julien XII is a ring-tailed lemur who is the maternal uncle of King Julien XIII. He kept the lemurs in soul crushing silence in order to avoid Fossa attacks. When Masikura tells him that "the one who holds the crown will be bitten by the Fossa," he gives up his crown to Julien so that he won't be eaten. According to Masikura and King Julien, he never apologizes and everyone was afraid to stand up to him and anyone who does he had banished. When King Julien XIII thrives as king, his devious uncle will do any conniving thing to regain the throne.
King Julien XIIl
King Julien XIII used to think well of his uncle and remembered him fondly when he moved, but completely lost his good perception of him once he and his kingdom got held captive in "The Man in The Iron Booty."