Stardust

Stardust was a Diamond Dog who was honored as a statue that guarded the Appaloosan Mountains alongside Ziggy.

History
The statues of Ziggy and Stardust, while in good shape, was being taken over by nature and beginning to crack, implying he may have been a quite ancient Diamond Dog, possibly a former ruler. The Mane Six passed by the statue when on their quest to save the Cutie Mark Crusaders from Queen Chrysalis in the Changeling Empire.

Behind the scenes
Paired with a Diamond Dog named "Ziggy", Stardust is obviously a play on the term "Ziggy Stardust", a persona used by David Bowie, which continues the trend in which Diamond Dogs names are David Bowie themed.