The week-long Halloween festivities have officially begun and it's safe to say that New York's chicest fashionistas have been having the most fun. After all, this is a holiday that's all about dressing up. 

On Saturday night, the city's most stylish cool kids, socialites, and fashion world celebs flocked to the Top of the Standard's annual bash, and, needless to say, the looks did not disappoint. While some attendees stuck to the invitation's western theme, plenty others, including Nicky Hilton, Ellen von Unwerth, May Kwok, and the night's A-list performer, Mya, went full glam for the occasion.

Click through for the must-see costumes of the night - maybe you'll snag some inspiration for your October 31st celebrations.

[Nianga Niang, Raphael Portet by Benjamin Lozovsky/]