Zillions of Zombies — Derek the Ghost

Eleven-year-old Charles Nukid thought he was the luckiest kid on earth when he was crowned the new monster king. But when he's challenged by a gang of angry trolls who don't think a human should be the monster king, something goes horribly wrong that turns all of the zombies of the world to evil and ravenous for brains. 

Charles's friend rush to Monster Kingdom to help him, include Lattie the Ninja Girl, Petunia the purple girl, his biggest crush Penny Possum, Dr. Dragonbreath, and Johnny the Sasquatch. Together they'll have to find the one unicorn left on earth whose magic is powerful enough to turn all the zombies back to good. 

Thrills, chills, laughs, and  a Zombie T-Rex will all be found in this fantastic final book. What more do you want??