Marvin

Marvin first appeared in Doug's Moai Adventure. He has since shown up in the Doug the Ogre webcomic. 

History
Marvin worked as a groundskeeper on Easter Island. When Doug came through the portal, he mistook him for an alien. Doug used this to his advantage, convincing Marvin to give him the key to his locker, so he could grab a ladder to reach the portal and get back home.

Marvin later used Merlin's belt to go through the portal and track down Doug. He gave Doug back the belt, and Merlin warned Doug to be more careful with it, lest it fall into the wrong hands.