Luca Signorelli (about 1441 - 1523), A portrait of Niccolò Vitelli, Città Di Castello, Central Italy, about 1492-6, oil on wood. Purchased 1945 (No.45.3). The Barber Institute of Fine Arts.

Niccolò Vitelli (1414 – 1486) was a ruthless mercenary commander who established his family as rulers of Città di Castello. 

This portrait was painted after his death. It was probably commissioned by his sons as a memorial, and it originally hung with their portraits. The profile portrait was used on coins and medals and it therefore held associations of power and of memory. In this case, the format also made it easier for Signorelli to depict the deceased.

(source http://barber.org.uk)