Last weekend in NYC, Valentino, Woody Allen and Derek Blasberg attended Allison Sarofim's Annual Halloween Party, Fiona Byrne, Atlanta de Cadenet, Alexa Chung, Joan Smalls and Rebecca Minkoff all got dressed up for The Byrne Notice & Emerson Halloween Party at Mister H, Jacquelyn Jablonski and Lindsey Wixson got in the spirit at Maison O, and so much more!