What is the highest class of mage?

I'm curious, could you elaborate on the hierarchy of mages and particularly, what is considered the highest class of mage? Are there specific qualifications or achievements that one must attain to reach this esteemed level? Is it a title bestowed upon a select few, or is it a skill level that can be gradually achieved through dedication and practice? I'm eager to understand the intricacies of this mystical hierarchy and the significance of the highest class of mage within it.