Was designed in 1963 by Adolphe Jean-Marie Mouron a/k/a Cassandre
That logo was designed by 1963 Adolphe Jean-Marie Mouron a/k/a Cassandre , a Ukrainian-French painter, commercial poster artist, and typeface designer. That YSL logo never withered over time. It can be reduced to monochromatic severity or overlaied in orange and fuscia and still remain totally and eternally YSL. It's minimal and feminine, deco and disco. It testifies to the wisdom of judicious choices and relentless taste.