Ka is an evil shadow monster who battled against the Monkey King and his companions.
The Monkey King destroyed him by summoning all of his energy in a blast that turned Ka into millions of shadow shards, but sadly the Monkey King was gone too. Then the Monkey King's five companions spread in the land of Ook and then built five tribes called Mek-Tek, Ice Raiders, Chim Foo, Sea Dragons and the Ootu Mystics. Now, monkeys are trying to get the Monkey King back, at least his soul or spirit. But Ka has returned to Ook and now he is planning to rule the monkeys, make them his minions, and destroy every single peaceful thing in Ook.