Timberlake joined his wife as a giant microphone.
"This is what happens when you admit on TV that you don't know any 'NSYNC songs and you're married to @justintimberlake Well played husband, well played," Biel captioned the image. The actress recently discussed her unfamiliarity with 'NSYNC on The Tonight Show.
Cardi B, meanwhile, wore a a red and white nurse costume. The rapper completed the outfit with red hair and red high boots.
"Last night was so sick," Lovato said next to a collection of Halloween photos.
Ashley Graham proudly displayed her baby bump while dressing up as Jessica Rabbit from Who Framed Roger Rabbit. The model was joined by her husband, Justin Ervin, who dressed up as late professional wrestling icon Macho Man Randy Savage.
"Macho Man knocked up Jessica Rabbit for Halloween," Graham said.
"My baby!!!!!!!! I can't handle this!!!!!" Jenner said.
Nina Dobrev dressed up as singer Billie Eilish. She pulled off the look by adding green to her hair, wearing an orange long-sleeve shirt, multiple silver chains, sunglasses and black makeup running down her cheeks.
"DUH," Dobrev captioned a video of herself in costume as Eilish's music played in the background.
Hurley's photos featured the actress wearing Thurman's yellow jumpsuit with the film and posing with a sword.