06/18/2010 07:59 am ET Updated May 25, 2011

Ashley Olsen, Maggie Gyllenhaal At The YSL Belle d'Opium Party: Who Was Best-Dressed? (PHOTOS, POLL)

Fashionistas in many forms turned up to Thursday night's YSL "Belle d'Opium" fragrance launch in NYC. In fact, we're not quite sure what the dress code was. Maggie Gyllenhaal donned a strapless magenta dress, model Irina Shayk opted for a shrunken (and tight!) leopard jumpsuit and Ashley Olsen wore a trenchcoat and a headscarf. Take a look at the pics below and let us know who was the belle of this ball, and whose ensemble was a bust.


For more party photos go here.