Nearly every little girl wants to be a princess -- particularly one of the Disney variety, the retailers agree. Princess was the top response in the kids' category for the retailers' survey, with "Disney Princess" tied at ninth place with Batman, vampires and zombies. But tweens have really taken to "Monster High" costumes, Tomkiewicz says.
The franchise, based on a line of Mattel dolls, features the children of the world's most famous monsters attending high school together.
"It's a good solution for girls who have sort of outgrown the Disney princesses," she says. "Hannah Montana just isn't as popular."
Tweens and teens alike might be attracted to the "zombie teen prom queen" Halloween costume, she says. It costs $29.99.
Siegel-George says Glee costumes, such as a $39.99 cheerleader outfit and a $49.99 tracksuit, have seen an increase in sales. True "Gleeks" can also add a branded megaphone for $14.99.