Bully Callum

Bully Callum is a character who appeared in Callum: The Show in a flashback to when the Callums first went to Callum School where he is seen looking for another Callum to pick on. Bill Callum was seen to have been a friend of his. During the flashback Bully Callum decides to try and pick on Hedgehog Man but is ultimately stopped by Callum, Professor Callum and then Bill Callum who turns on him.

In the flashback he tells the Callums "I'll leave him alone but in future you guys better watch your backs because I may be coming for ya".

This character was revealed to be Mullac in The Supercat Video Universe: Volume 2 after Bill Callum accidentally meets him again after many years.