Halloween Costumes and Halloween Costume Ideas for Kids and Adults. Everyday low prices, pick up discount on eligible items and free shipping on all orders over $ Halloween supplies, decor, materials and accessories to create the perfect Halloween costume and Halloween costume or themed party! We have adult costumes in many sizes and styles. We carry sexy adult Halloween costumes as well as plus size Halloween costumes for men and women. Shop for Adult Halloween Costumes in All Costumes at Walmart and save. Find popular options like Harley Quinn, Jack Skellington, Star Wars and Ghostbusters costumes for the lowest prices.