Self-portrait: earliest found.
by Self-Portrait of the Artist
The altar of Sant’Ambrogio, Milan, carries the earliest self-portrait in Western art I could find, dating approximately 824-859, during the Carolingian rule.
The Latin inscription identifies the artist as VVOLVINIVS MASTER PHABER (Vuolvinius, Master Goldsmith). But it is not the actual resemblance that counts (the character-traits are pretty generic) as much as the words that name the artist, his respectful pose, and the blessings and golden crown he is given by patron saint Ambrose, for whom the artist made his work.
This type of portrait is crucial better to understand the revolutionary, new-found naturalism of a Ghiberti, already a modern man.