Krampus is a German legend, and Mystery Inc. 's monster, used as a distraction to the original gang.
The gang put the costume over Charlie the Haunted Robot. Jason Wyatt controlled it. The gang chased after Krampus, pretending it was a usual mystery, and the original gang chased them, wanting the disk pieces. Krampus was unmasked after taking Mary Ann Gleardan to the abandoned doll factory. The original gang stole the disk pieces, but they were fake. They arrived at Mr. E's lair and got a message from the current gang, about how they made Krampus (Wrath of the Krampus)