Gone are the days when you could throw a sheet over your head and call it a Halloween costume. Halloween is serious business. Retailers expect Americans to spend about $8 billion on the day,according to a National Retail Federation survey conducted by BIGinsight.

Of course, part of the fun of the holiday is coming up with a creative Halloween costume. About $1.1 billion will be spent on children’s costumes this year.

For kids, there will be plenty of the traditional costumes: princesses, super heroes, witches and pirates. But even these popular themes are subject to interpretation.

We’ve taken a look at what the trendiest costumes are for kids this year. Click ahead to find out what they are, some may surprise you.

By Christina Cheddar Berk
Posted 28 Sept 2012

Suggested Price: $34

Give a hoot, this baby is cute.

Forget the ill-fitting vinyl costumes. These days, the selection of adorable baby and toddler costumes seems endless, so it will likely be a tough call when it comes time to select a costume for Halloween.

Suggested Price: $29

After trick or treating, it will be back to the pen for this guy. That is, unless, the warden gives the kid a break for good behavior, so maybe it'll be the play pen.

Suggested Price: $19.99 to $34.99

Pirates are a popular theme and typically rank within the top 10 each year.

Fans of Disney’s (DIS)“Jake and the Neverland Pirates” may want to check out the costumes for Jake and Izzy that are new this year. Accessories, sold separately, include a soft sword and a treasure-chest-shaped treat pail.

Suggested Price: $29.99

This is expected to be a big year for super hero costumes. Halloween retailers expect both boys and girls to hop on board the trend.

According to the National Retail Federation’s survey, Batman will be the second-most popular costume (behind princesses), followed by Spiderman in third. But Halloween costume retailers said the release of Marvel’s Avengers has given new life to sales of super heroes that had tended to be less popular in years past.

They expect sales of Hulk costumes to rise significantly. Iron Man and Captain America also have new fans.

Costume manufacturers continue to broaden the array of choices of style. The super hero costumes pictured here are from Jakks Pacific’s Disguise unit and have soft muscles and soft accessories, which are popular with little kids.

According to Cheryl Kerzner, vice president of design and marketing at Disguise, young kids tend to wear their Halloween costumes long after the holiday has come and gone. These costumes don’t have hard pieces that could pose a problem if a child wanted to wear the costume to bed at night.

Suggested Price: $68

Although ninja costumes don’t rank among the NRF’s 10 most popular costumes of the year, retailers say they are gaining in popularity. This ninja warrior is ready for battle. The six-piece set includes a mask, tunic, hooded chest piece, belt, pants and sword.

Suggested Price: $24.99

Monster High costumes were a big seller last Halloween, and they’re back. Their popularity should only grow with the addition of new characters to the line. Pictured here is the Rochelle Goyle costume, which is available at Spirit Halloween.

Suggested Price: $34.99

Costume retailers expect to see the continued popularity of characters based on videogames and apps. Plenty of characters from “Angry Birds,” “Mario Brothers” and “Sonic the Hedgehog” will be knocking on the door, looking for candy.

This year, they will likely be joined by characters from the popular Activision (ATVI)game “Skylanders.” The videogame has been a bright spot amid slumping game series. Pictured here is Spyro, the magical dragon.

Suggested Price: $39.99

Costumes like the panda and tigress, pictured here, are expected to be popular with teens. They are easy to wear to parties and demonstrate how manufacturers are beginning to design costumes that wear more like apparel than the flimsy costumes of the past.

Suggested Price: $49.99

With the huge popularity of “The Hunger Games” trilogy, expect to see lots of teens dressed as Katniss Everdeen and other characters from the series.

Suggested Price: $79

Grown-ups aren’t the only ones looking for some humor in their costumes this year. According to Karen van Ert, chief marketing officer of Buy Seasons, shoppers are looking for costumes that will make you laugh. “Gnomes are very popular this year,” she said.

Suggested Price: $44.99

Katy Perry costumes were popular last year, but some were not that appropriate for Perry’s younger fans. This “Candy Girl” costume, new this year at BuyCostumes.com,should hit the spot.

Suggested Price: $69 for the costume
Accessories: $9 and up

There is no end to the many variations on the “princess” costume. No wonder it remains the most popular children’s costume for Halloween. Girls looking to put a different twist on the idea may want to consider this “Galaxy Princess” costume.

The costume may be a bit out of this world, but it’s not off trend. Neon colors in costumes are hot this year.