Alyssa Milano dressed her little pups as yummy tacos, while the pups of singer Aubrey O'Day morphed into a bunny and a mermaid.
Modern Family star Sarah Hyland's Maltipoo Barkley went rogue dressing as a "little devil bat dog." And actress Chloë Grace Moretz doted on dog Jaxon who was a witchy villain.
"I'm a baby dog witch," Moretz wrote on Twitter. "No big deal. He's just the cutest thing you've ever seen."
Perhaps the scariest of all was Paris Hilton's dog, who transformed into a little monster that only a mother could love.
"Loving my puppy Harajuku’s @LadyGaga costume," Hilton Tweeted with a photo of the dog wearing a blonde wig and wacky shades.