That's the Eastern Roman/Byzantine Emperor Justinian, based off of this mosaic image in the Basilica of San Vitale in Ravenna.

I thought that was Anna Komnene since she wrote the Alexiad and is, or should I say was, a well known historian. :O

As it turns out, Snoostian's robes are not distinguishable from a dress at reddit alien sizes. Also, I like to think that the writing-board he's holding has the Corpus Iuris Historiesnsis.

I always thought it was a Byzantine emperor