Americans are expected to spend more than $1 billion on costumes for their children and $310 million to dress up their pets, according to the National Retail Federation, an industry trade group.

Although many young adults hunt for original looks, when it comes to finding a costume for the kids, traditional themes usually win out.

That’s not to say everyone will be dressed alike. More retailers are selling costumes, and this means more choices for consumers.

Costumes for kids and pets tend to draw their inspiration from typical Halloween characters, as well as popular movies and books.

For example, Williams-Sonoma’s Pottery Barn Kids stores sell a number of costume designs for children and infants. Among them are costumes based on Eric Carle’s classic children’s book “The Very Hungry Caterpillar.”

Children can opt to dress as the caterpillar or the butterfly it becomes.

Pottery Barn’s costumes tend to have a more homemade look to them and are priced at the higher end of the range for typical children’s costumes. Customers also can buy matching bags for trick-or-treating.

Click ahead to see some of the hottest costumes for kids and pets this year.

By Christina Cheddar Berk Posted 5 October 2011

Pictured: Zombie Costume
Retail: $39.99

Zombie costumes rank among the most popular Halloween themes this year.

According to the NRF’s Top Costumes survey, conducted by BIGresearch, more than 2.6 million men, women, and children plan to dress as zombies this Halloween.

Zombies have always been a traditional Halloween costume theme, but recent books, television shows, and videogames about zombies have made them even more popular. There also have been scores of so-called zombie crawls, where people gather dressed as zombies.

Zombie costumes jumped from No. 22 last year on the NRF’s list to No. 9 on the children’s top costume list, and from No. 7 to No. 4 on the adult list.

One startling thing about the trend is that younger children are also dressing up as zombies.

Pictured: Goth Prom Queen
Retail: $34.99

There also is a wide array of zombie costumes out there. Almost any Halloween costume theme can be turned into a zombie.

This year retailers are selling a Zombie Fairy Girl costume, a Zombie Ninja, and a Rocked Out Zombie — even a Zombie Sock Monkey costume!

There also is a strong gothic theme that is somewhat related to zombies. As with the zombie, there are many ways to interpret the gothic theme.

Pictured: Frankie Stein
Retail: $24.99

One of Mattel’s recent successes has been its line of Monster High dolls. The dolls’ characters are inspired by monster movies and horror fiction, and were introduced in a series of webisodes set in a high school called “Monster High.” The dolls have been a big seller and so has a line of costumes based on the characters, according to several costume retailers.

Most of the main characters are supposed to be the children of famous monsters, including Dr. Frankenstein’s monster, Count Dracula, and the Werewolf.

Pictured here is one of the most popular characters, Frankie Stein.

Retailer Spirit Halloween also sells several costumes based on Lalaloopsy, another line of dolls that are currently very popular.

Pictured: Angry Birds
Retail: $21.99

A line of costumes based on Rovio’s Angry Birds game also is very popular this year.

Versions of these costumes were designed for all ages, including this bunting version for infants.“The popularity of the Angry Birds costume caught us by surprise,” said Brad Butler, a spokesman for Halloween Express. “Right now, it’s the No. 1 selling costume.”

Pictured: Wario Deluxe Costume
Retail: $29.99

Last year, there were plenty of kids trick-or-treating as Mario, Luigi, and Princess Peach. In fact, the costumes were so successful that manufacturers have expanded the Super Mario Brothers line for this year.

The evil doppelgangers of the Super Mario game, Walugi and Wario, were added, giving fans of the popular video game even more choices for Halloween.

Pictured: Elephant Dog Costume
Retail: $38

Man’s best friend will also be getting into the Halloween spirit this year. In recent years, spending on costumes for pets has climbed. Like last year, the most popular pet costume is a pumpkin. In an NRF survey, 10.7 percent of people who said they planned to dress up their pets were going to dress them in this type of costume.

Devils (8.1 percent) and hot dogs (6.0 percent) round out the rest of the top three.

Ironically, some pet owners also like to dress up their pet as a cat (3.7 percent) or a dog (2.0 percent).

This elephant costume, sold by children’s boutique Chasing Fireflies, is a bit more exotic.

Pictured: Strawberry Shortcake
Retail: $32.49

There was a huge Strawberry Shortcake fad in the 1980s, and the character is seeing renewed popularity thanks to the Hub, a TV network operated by Discovery Communications and toymaker Hasbro.

In addition to Strawberry Shortcake, children can choose to dress up like one of her friends, such as Blueberry Muffin or Lemon Meringue.

It’s also a costume choice that appeals to many mothers who remember the character from their childhood, said Cheryl Kerzner, vice president of Product Design and Marketing at Disguise, a costume manufacturer owned by Jakks Pacific.

Pictured: Captain America
Retail: $34.99

Superhero costumes are always popular at Halloween. This year, new movies have sparked interest in characters such as Captain America, the Green Lantern, and Iron Man.

There also are sure to be plenty of kids dressed up like Transformers, and characters from X-Men Wolverine.

According to the NRF, Spiderman is the third most popular costume for kids, and Batman ranks eighth, in a tie with vampires.

For most of these characters, retailers sell costumes for both girls and boys, as well as for pets.

Pictured: Patriotic Pup
Retail: $18

Some pet owners opt to dress their pets in fancy collars, bowties, and bandanas. For those who want to kick the bowtie up a notch, there is this patriotic costume.

Pictured: Golden Queen
Retail: $98

Of all the costume themes, the princess costume reigns supreme. According to the NRF, 11 percent of kids will dress up like a princess, and an additional 2.2 percent will dress as one of the Disney princesses.

This costume, sold by Chasing Fireflies, has plenty of royal touches — and a price tag to match. The satin gown has panel overlays, dramatic sleeves, and sequin trim. There also is detachable high-collar cape.

As for the Disney princesses, costume retailers are expecting to see a lot of interest for Disney’s Rapunzel, the star of last year’s animated feature “Tangled.”

Pictured (right): Smurfette Costume
Retail: $17.24

Pictured (left): Papa Smurf Costume
Retail: $24.99

Don’t be surprised if a little blue person knocks on your door this Halloween. This summer’s “The Smurfs” movie will likely inspire more than a few trick-or-treaters.

The Papa Smurf costume pictured here is from Target, but the discount retailer has already sold out of stock online for its Smurfette costume, as well as for its Smurf and bunting Smurf costumes.

Other types of Smurf costumes are also available at other retailers.