Isleworth Mona Lisa
According to Leonardo's early biographer Giorgio Vasari, Leonardo had started to paint "Mona Lisa" in 1503, but "left it unfinished". However, a fully finished painting of a "certain Florentine lady" surfaced again in 1517, shortly before Leonardo's death and in his private possession. The latter painting almost certainly is the one that now hangs in the Louvre. Based on this contradiction, supporters of the authenticity of the "Isleworth Mona Lisa" claim it is the unfinished "Mona Lisa", made at least partially by Leonardo, and the Louvre "Mona Lisa" a later version of it, made by Leonardo for his own use.
Lisa del Giocondo
Lisa del Giocondo (; née Gherardini ; June 15, 1479 – July 15, 1542) was an Italian noblewoman and member of the Gherardini family of Florence and Tuscany. Her name was given to the "Mona Lisa", her portrait commissioned by her husband and painted by Leonardo da Vinci during the Italian Renaissance.