Self-portraits have been made by artists since the earliest times, but it wasn't until the Renaissance that they became truly popular.
Rembrandt was the most frequent self-portraitist, at least until the self-obsessed modern period, also often painting his wife, son and mistress. At one time about ninety paintings were counted as Rembrandt's self-portraits, but it is now known that he had his students copy his own self-portraits as part of their training. (Wikipedia)