Wyrm

Wyrms come in many varieties, but they do have a few things in common: They are all, to some extent, large and lizard-like, they all have natural connections to Magic, and they can all shapeshift into humanoid forms. 
There are two classifications of Wyrm: Greater Wyrms and Lesser Wyrms. Greater Wyrms, such as Dragons and Linnorms, are those powerful enough to be Magical patrons. Lesser Wyrms, such as Wyverns and Hydras, are those who cannot be patrons. Lesser Wyrms are typically descended from Greater Wyrms.