The Warrior Librarians, also known as the Warrior Librarians of the Eternal Archives, are keepers of the most dangerous books ever written in Skylands, and are the kind of people many don't want to cross. They are actually small worms that operate silver armor suits to help them protect the Eternal Archives. They made their debut in the Mask of Power book series.
One of the Warrior Librarians, Squirmgrub, is revealed to be a traitor and was giving Kaos the locations to where the pieces the Mask of Power are found.