The Famous Stilicho Diptych - Actually Depicts Aetius

[Liburnius]

I am late to this discussion, but I have just gotten around to reading the PDF in the link. Thank you for sharing this excellent new information! I was aware of one other depiction that's meant to be of Aetius, but I had long equated the one in this study with Stilicho. If these are both supposed to be of Aetius, then is there now no longer any known image of Stilicho? It would be interesting to know what he looked like, as at least on the internet search results I've come up with, late Roman busts, portraits, and other artistic depictions of individuals appear to be rather rare compared to earlier imperial years. Interestingly, Aetius' own depiction seems remarkably different, when comparing the two. For one thing, he is beardless in one of them, and with a wider nose and jaw.

[Flavivs Aetivs]

It's really up in the air. The Monza Cathedral Diptych can be narrowed down to Aetius or Stilicho, but we can't say for sure it's either one. I like to think the Stilicho Sarcophagus in Milan is of Aetius (a theory that's been hanging around for about a hundred years) but again, we don't know. It could be of a number of Late Roman men of authority and now it's thought to date to the late 4th century, not the 5th.

[Nathan Ross]

I like to think the Stilicho Sarcophagus in Milan is of Aetius... but again, we don't know... it's thought to date to the late 4th century, not the 5th.

Very unlikely to be Aetius, I think - the sarcophagus itself seems to date from c.385, as you say, but it's cobbled together from bits of earlier sarcophagi, some of them could be as early as the 3rd century. The medallion portrait of the man and his wife looks rather mid-4th century to my eyes.

Aside from the Monza diptych, whoever it is, the only other 5th century portrait of a military subject I can think of is this one, of Aspar and Ardaburius, in their magisterial robes:

[Flavivs Aetivs]

You forgot the Diptych of Felix (428, which the Monza Cathedral Diptych is typologically most similar to), among several others.

You posted the Missorium of Ardaburius Aspar (roughly around 470 AD, can't remember exactly when), the son of Ardaburius. Both men were Alans who served under Theodosius II, they led the campaign that installed Valentinian III in 425 and Aspar and Boniface fought against the Vandals from 431-435. Aspar in some ways became the "Stilicho/Aetius/Ricimer" of the East.