Leonardo da Vinci Self Portrait
Master Copy - Reconstruction
The original can be found on a sheet of doodles and writings in the Royal Collection at Windsor Castle known as the "Fioravanti Folio": It is a small and very swift line drawing that Leonardo did in 1478, and is generally believed to be a self-portrait.
Using Leonardo's sketch as a guide for his facial features - wind-swept hair included - I reconstructed (or perhaps filled in?) what he would have looked like at the age of 26.
Original post of this on my tumblr with another link to a self portrait reconstruction, just for good measure.