Kate Hudson and ex-fiance Matthew Bellamy reunited to take son Bingham trick-or-treating Saturday night.

Kate went as a sexy ninja (how could she be anything other than sexy) and Matt went as a bearded wizard, while son Bing was a very scary zombie!

Meanwhile, Fergie and Josh took son Axl out for some candy. This trio really goes all-out! We can't decide who's cuter, Josh or Axl!

Alessandra Ambrosio was out with the family, all looking dolled up and adorable for the holiday. And Jordana Brewster was a perfect Elmo, while her son Julian was a cute little munchkin!

Denise Richards took her crew out for some candy -- an adorable nerd and Alice in Wonderland, making an appearance. While Alyson Hannigan and her family dressed in spectacular costumes, as usual. Alyson's a witch's cauldron, but what's her hubby dressed as? We love the costume, we just can't figure it out! Swamp monster?