Well.
A princess (Snow white, Repunzel, sleeping beauty, Cinderella, etc...)
A fairy ( a dark fairy or fairy princess?)
A rag doll
A dancer
A viking
A vampire
A power ranger
A cheerleader
A punk
Any of the wizard of Oz Characters
A Business Person
A gymnast
A Gangster
A Clown
A Super Hero
A Singer (Lady Gaga, Taylor Swift, Selena Gomez, Justin Bieber, etc)
A Werewolf
Someone from Grease
A Ladybug
A Bumble Bee
A Butterfly
A Caterpillar
The Cheshire Cat
Alice (from alice in wonderland)
The mad hatter
A Pumpkin
A police officer
I hope that was enough, and I hope i helped :)
I would also suggest maybe a cheetah or devil or angel or half devil half angel
Well most 11 year old girls don't like things that are too girly and too grown-up, so things like movie characters, video game characters, tv show characters, funny costumes, and classic costumes (ie: devil, angel, ghost, vampire, monster, Dracula, etc.) are good ideas. Also being characters that are from toddler shows like Elmo's World makeup seem funny.
Monster High costumes are cute, but be warned… These school girl costumes are more Britney Spears than little girl
Vampire but not with a cape, a cute miny skirt and blouse
Referee if you like sports
Half devil half angel
just go to a halloween store or website and they have a lot of ideas. you can also get a costume that has to do wit your hobbie
you can find more information on girl's halloween costumes online at halloween city.com. there they have cute but tasteful costumes for young girls to wear. they also have some for the teenage girl as well.
Little red riding hood or like a nerd
It'm amazing how simple a good costume can be to make! Look at http://familyfun.go.com/halloween/halloween-kids-costumes/ for some good ideas. Happy Halloween
80's aerobic instructor Hermione from Harry Potter a Cheerleader
There are many great scary costumes for women! Bride of frankenstein, witch, or even a zombie are some ideas. Here, this website sells some spooky costumes for woman: http://www.frightcatalog.com/Halloween-Costumes/Womens-Costumes/Horror-Costumes/
Here are some ideas for women's Halloween costumes: librarian, your favorite type of candy bar, a flasher, a cat burglar, a flapper girl, or a kissing booth.
There are several online stores that sell a wide variety of Halloween costumes. Some of the most popular sites are buycostumes.com, costumesupercenter.com and anytimecostumes.com all these has a great selection for kids and adults.
Some excellent ideas for couple Halloween costumes include past presidents like Hillary and Bill or Bonnie and Clyde. You can get costumes at Party City or even stores like Target.
Some good ideas for costumes for couples include Marge and Homer Simpson and Lucy and Ricky. They make for great costumes!
It depends on the girl and the type / personality of her. Some classic ones are princesses, witches, ghosts, vampires, and sports-players / cheerleaders.
Some good homemade halloween costumes could be for one the original witch or even a pumpkin. Easy, fast, and fun! You could also do frankenstein and the bride for couples.
There are some good websites that have ideas for couples costumes. Sexycostumes.com has some choices for different sexy sailor costumes, plus many other ideas.