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.
Cesare Maccari
In 1863, Maccari painted "Leonardo che ritrae la Gioconda" (commonly translated "Leonardo [da Vinci] painting the Mona Lisa") which won an award in 1865. In his home town Siena he decorated the "Sala del Risorgimento" in the public palace with frescoes that were well received by critics.