Master

"Master" was the title given to what seemed to be an ancient ruler of the, or a Diamond Dog society.

History
The Master appears to be an ancient figure, but not so ancient that the words inscribed in his statue are in the Olde Equestrianne language. He seemed to have a lover, though she may have simply been a slave as she was seen mining for diamonds. The master seemed to be a cruel individual who forced his workers to work in inhumane conditions to appease his greed.

Behind the scenes
The Master first appeared in as a statue, like Ziggy and Stardust before him.

A similarly appearing Diamond Dog appeared in the Convocation of the Creatures arc as an apparent ruler and/or delegate of some Diamond Dog society, though apparently not that of the kingdom of Caninia.