Perugino's Bust of St. Sebastian

                     
Perugino, Bust of St. Sebastian (1493-4) Hermitage          Detail of Bust of St. Sebastian

In this early painting of St. Sebastian by Perugino the artist signed his name as though it was the arrow: "Opus Peruginus Pinxit." To any other painter on the same wavelength the meaning behind the substitution would have been clear: St. Sebastian is an alter ego of the painter and the arrow symbolizes his brush. Thus since the brushes pierce or "paint" his alter ego, the painter paints himself.  

See Carlo Crivelli's Altarpiece with Saint Sebastian painted the same year.