Oh. He's an active part of the Santa mythos in various European countries.
Essentially while Santa is out rewarding all the good children with gifts, he has a partner who handles the more serious aspect of punishing the bad children. Usually with filling their stockings with such things as Coal, goat bones or just leaving switches for their parents as a message that they need to discipline them better.
He's often depicted with dark skin, and there is some current debate on wether he is meant to be a slave to St. Nicholas or maybe even the Devil. Personally I don't think either of these is accurate as no sensible person would leave the punishment of children in the hands of either the Devil or a Slave.