Arndor was a bandit who was briefly mentioned in The Sorcerer in the North.
He was a giant of a man, standing over two metres tall and terrorized the people living in the town of Crewse in Araluen. He is mentioned by Halt after Will gives John Buttle into slavery. Halt compares this action to that of a Ranger who arrived in the town of Crewse. The Ranger in question bested Arndor, chained him to a mill wheel and let the townspeople use him as a mill pony for a period of five years. Apparently it brought the town a bit of prosperity as well as Crewse became known for its fineness of grain.
Crowley inadvertently reveals himself to have been the Ranger, trying to make excuses for his actions during the event.