Portrait of a Young Man is an oil on panel painting by Parmigianino, executed c. 1530, now in the Uffizi in Florence, whose collection it entered on 27 October 1682. Three copies survive in the Museo di Capodimonte (n. 201), Rome's Accademia di San Luca and the Galleria nazionale di Parma (n. 313, inscribed with the date "MDXX", which is probably also the date of the Uffizi work).
https://en.wikipedia.org/wiki/Portrait_of_a_Man_(Parmigianino)
Could also be a Highlander style immortal. Let's not rule anything out.