Boo! There were spooky surprises in store this week when Instagram's most chic got wicked with their fashion. Our favorite snappers like Alexa Chung, Poppy Delevingne, Joan Smalls, and Derek Blasberg looked scary-good in their haunting designs as they prepared for Halloween  in over-the-top style. Click through to see this week's best shots, and don't forget to keep up with our editors by following us at popsugarfashion !
Grace Coddington had no superstitions about Stephen Jones's black cat.
As if Rosie Huntington-Whiteley could get any hotter, she piled on leather and chains.
Harley Viera-Newton was one hot dog.
Tom Brady  and Gisele Bündchen  made for a storybook couple in their adorable costumes.
Giancarlo Giammetti and Valentino Garavani got into the act at their masquerade party.
We're not sure what Joan Smalls was, but it's pretty incredible!
If ever Dolce & Gabbana decides to go into the mask business, Stefano Gabbana's feathered style would be a good place to start.
Not to be outdone, Anna Dello Russo was finely feathered too.
Gwyneth, is that you?
The Minkoff family became the Addams family for a night.
Any guesses as to what Derek Blasberg had in mind for his costume?
Would you like fries with that?
Atlanta de Cadenet was skin and bones in her ghoulish makeup.
Laura Love's pumpkin had a view.
We're thinking Nicole Richie  would be perfect for a Twins remake.
Jacquelyn Jablonski looked terrifying and terrifyingly pretty at once in her veiled garb.
How's this for meta: an Instagram of an Instagram.
Bryanboy scoped out the festive scene at his New York bash.
Trick or treat? Why not both?
Stripes kept these costumes coordinated and totally on-trend.