Barbie has some monster-sized competition.

Back in 2010, Mattel launched its line of Monster High toys, which have gone on to scare up some serious interest among fans.

Monsters High sales are up 56% this year, while Barbie's sales continue to creep down like her dream house in a mudslide. What's interesting is that Monsters High, a collection of gothic dolls with Garbage Pail-like names, is designed for girls between the ages of 6 and 12 – a demographic that Barbie has owned for decades.

Monster High is now the second bestselling doll on the planet, trailing only – you guessed it – Barbie. It features a line of dolls, as well as books and shows online.

Monsters High features a collection of two dozen or so characters, including Frankie Stein, Draculaura and Howleen Wolf. Call it Mattel's way of capitalizing on the current vampire-zombie craze.

So, what makes these offbeat characters such a hit? A Mattel spokeswoman said, "The message about [Monster High] is really to celebrate your own freaky flaws, especially as bullying has become such a hot topic."

Other companies have taken notice, too. Disney plans to keep up by introducing its own frightening versions of classic characters Snow White, Cinderella and Peter Pan with Once Upon a Zombie.

Which begs the question: will Mattel be able to put a stake in its competition?

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