Last summer I went to a discussion at the Edinburgh Book Festival entitled "Where have all the brave girls gone?"Judging from the packed theatre, a lot of people were interested in the question that the speakers, chaired by Kate Mosse, were posing – namely, when there are so many great heroines in children's literature, why do women often seem to be relegated to supporting roles in teen and adult books? Certainly it cannot be doubted that there are some brilliant heroines in children's books. Clarice Bean, Pippi Longstocking, Roald Dahl's Matilda and Mildred Hubble, the worst witch, are just a few that spring to mind.

The main thrust of the discussion was that in teenage and adult books sparky, independent heroines become increasingly less common as girls come to be defined by their love lives rather than their adventures.

Male characters can be defined by romance too - think of John in I Am Number Four. Photograph: DreamWorks Pictures/Film Frame

When you look at teenage fiction, it does seem true that virtually all female protagonists have to be involved in some kind of romance. However, the same could equally be said of male protagonists. Think of John's love for Sarah in I Am Number Four by Pittacus Lore, or of James Adams mooning after Kerry (and various other girls) in Robert Muchamore's Cherub books. As for Rick Riordan's novels, Percy Jackson, Jason Grace, Frank Zhang and Leo Valdez all seem to spend as much time thinking about their girlfriends as they do fighting monsters. Compare these characters with Lyra in His Dark Materials by Phillip Pullman, Katniss Everdeen, star of Suzanne Collins' Hunger Games trilogy or Meggie in the Inkheart books by Cornelia Funke. From these examples alone, it seems clear to me that authors are writing teenage books with strong female protagonists, and while these heroines might have love interests, they are no more central to the plot than in many books with male protagonists. So why is there this perception that teenage books featuring girls are mainly concerned with romance and relationships, while those starring boys are all about macho adventures?

Julia Golding, Girl on the Run: Ringmaster

Part of the blame, I think, must lie with the publishers. The gender politics of book covers was one of the issues raised at the discussion in Edinburgh, and the Darcie Lock books by Julia Golding are a case in point. For those that haven't read them, they are a little like the Alex Rider books in that they involve a teenager being used as a spy by MI6, except that they are better in every conceivable way. When Darcie's Dad, an undercover agent, goes missing in Ringmaster, MI6 recruit Darcie to help track him down. As events spiral out of control though, she becomes involved in battling international smugglers and thwarting a group of Kenyan extremists intent on assassinating a British prince. The original book cover reflected this thrilling tale of espionage and corruption, with a graphic design composed of fast cars, abseiling SAS men, polo players (don't ask – just read the book) and the Nairobi skyline.

Julia Golding, Deadlock

Recently though, I came across a new edition of the book. The cover now shows a gold and diamond pendant in the shape of a zebra (Darcie's code name). What? Why? To anyone looking at this cover, Ringmaster would appear to be a novel about an ultra-fashionable teenage socialite, rather than an adventure story featuring spies, bombs and army training. On the cover of the most recent books in the series, Deadlock, there is a picture of a pretty teenage girl with Kate Middleton-esque hair gazing wistfully into the distance, wearing mascara and a white lace vest top – something the real Darcie wouldn't be seen dead in. Across the top of the cover it says "Darcie Lock is every boy's dream. Beautiful, smart… oh, and she's a secret agent". Excuse me?! What does her attractiveness to boys have to do with anything? And why are her looks mentioned before anything else, when she's not even meant to be that beautiful – good looking, sure, but that is nowhere near as important to her character as her intelligence, determination, sense of humour, athleticism and bravery.

Julia Golding, Den of Thieves (Cat Royal)

A similar crime has been committed against Julia Golding's other brilliant series of historical fantasies set in 18th century London (and beyond), which star Cat Royal and involve gang rivalry, theatrical drama, political intrigue, slave revolts and maritime swashbuckling. Again, the original covers reflected this. Recently though they have been rebranded with the ubiquitous cover of a girl's face, just like all Eva Ibbotson's books and pretty much every historical novel ever written that focuses on a woman (Philippa Gregory's books in particular spring to mind). Is it just that cover designers nowadays have no imagination, or is it that if the central protagonist is female, they automatically think it is her appearance that is important rather than her actions? Whether or not this is the message intended, it is certainly what these stereotypical book covers convey to readers. They also convey the message that these novels are only for girls, thus discouraging boys from reading some very good books and reinforcing the pernicious and outmoded gender split within publishing.

Another culprit is the film industry and its insistence on ironing out the differences between female characters until they all fit some Hollywood stereotype of feminine beauty. In the Percy Jackson books for example, one of the characters, Clarisse, a daughter of Ares, is described as having "long and stringy hair" and wearing "a size XXXL Camp Half-Blood T-shirt under a camouflage jacket". In the film though, Clarisse is regulation-hot, and dressed in a tight fitting vest top. Similarly, in Markus Zusak's heart-rending novel The Book Thief, the main character Liesel is a skinny, foul-mouthed scrap of a kid with dirty blonde hair. In the film, she has perfect golden ringlets, round cheeks and pouty lips – according to the adverts at least. They put me off so much I can't face going to see the film. Even in the Harry Potter films, which I absolutely love, Hermione, Luna and Bellatrix in particular are all made far prettier than in the books. And as for Ginny – she is transformed from a powerful, funny and independent whirlwind into a mere adjunct to Harry.

A perfect Disney princess: Liesel in The Book Thief Photograph: Jules Heath

So I would say that the brave girls haven't "gone" anywhere – it's just that after adolescence, they become harder to find, thanks to the frankly retrograde attitude of many publishers and film-makers. If you can look past the off-putting covers though, there are some amazing female characters in contemporary teenage fiction – individual, independent and, above all, not defined by some narrow, old-fashioned, gender stereotype.

I've already mentioned several of my favourite heroines in contemporary teen fiction; here are a few more:

• Sally Lockhart: Lyra from the His Dark Materials trilogy is often cited as a strong, independent-minded teenage heroine. Less well known, but just as brilliant, are Pullman's Sally Lockhart books, historical thrillers set in Victorian London. Sally uses her intelligence, determination and sharp-shooting skills to uncover the mystery of her father's death in the first book, The Ruby in the Smoke. She defies all Victorian conventions, having a child out of wedlock, running her own financial advisory business and taking complete charge of her own destiny.

Artemis Fowl by Eoin Colfer Photograph: Eoin Colfer

• Holly Short: Although Artermis Fowl is the eponymous hero of Eoin Colfer's books, for me it is Holly Short that really steals the show. A brave and determined soldier, the elfin LEP Captain is also intelligent, kind and fond of unconventional tactics. Add in Juliet Butler, Opal Koboi and Minerva Paradizo, and you've got one of the best female casts in teenage fiction.

• Kitty Jones: The Bartimaeus trilogy by Jonathan Stroud stars the djinni Bartimaeus, the magician Nathaniel, and Kitty Jones, a member of the Resistance against the magician's rule. By far the most admirable of the three, Kitty is quick-witted and brave, with strong moral principles. When Nathaniel, in his capacity as government minister, tries to arrest her, she punches him on the nose and makes her escape, and yet later goes on to save his life several times. She is mainly in the second and third books in the series, so make sure you read them all. She is awesome.

Frances Hardinge, Twilight Robbery

• Mosca Mye: With eyes black as pepper and accompanied by her homicidal goose, Saracen, Mosca careens through life leaving havoc in her wake. Her character alone makes Frances Hardinge's beautifully written books, Fly By Night and Twilight Robbery, well worth the read.

• Deeba Resham: Deeba is the un-heroine of China Mielville's fantastically original Un Lun Dun. Accompanied by half-ghost Hemi and a milk carton called Curdle, she steadfastly refuses to follow the rules, but instead conquers the evil sentient Smog in her own, inimitable, style.

Elizabeth Wein, Code Name Verity

• Julie Beaufort-Stuart, Maddy Brodatt and Rose Justice: The stories of these three incredible women are told in Elizabeth Wein's beautiful books, Code Name Verity and Rose Under Fire. Julie is a British spy, captured and tortured by the SS, while her friend Maddy is an ATA pilot who is part of the attempt to rescue Julie. Rose is also an ATA pilot who is captured by the Nazis and imprisoned at Ravensbrück Concentration Camp, where she meets the "Rabbits" – Polish women who were experimented on by Nazi scientists. These books remind all of us that it wasn't only men who suffered and died as spies, pilots and fighters in the Second World War. Lest we forget.

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Jon

I note that you have omitted digital publishing. Perhaps you would find rather better and more diverse tales there? For example:

Pandora, based on the Greek myth of Pandora's Box but with a modern twist, in which Pandora explores the unusual and sinister village of Willowcombe Clatford, wherein everyone is happy, content, attend church, and never, ever, question authority.

Or there is also The Vampire Project, a steampunk adventure in which working class Tamara Kelly and upper class Lady Roslyn Foxington are thrown together when they stumble on a secret project to turn humans into creatures of myth.

I mention these as neither involve any form of romance, or view the heroines as being in any way incomplete for their lack of traditional boyfriends. Indeed, The Vampire Project was a direct response to the Twilight saga, in which vampires are borderline abusive and controlling partners (bizarrely presented as a good thing) and teenage girls are pathetic, clinging stereotypes.

Jenny

I'd like to add that there have always been an abundance of books out there for young women to read having to do with their interests! Girls are often drawn to reading all by themselves, without too much prodding from parents and teachers. For decades, much energy has been put into ensuring that there are books available to girls and women, and they always have had female main characters who are savvy and independent. I still have books I read written in the 80s and 90s from when I was a teen. My point is that, although we've dealt with a lack of female lead roles in books and lead characters in books who are *primary* and *influential* characters for ages, I don't believe there is a lack on the bookshelf now. In fact, I'd like to see more intelligent main characters in books for boys besides underpants wearing captains and wimpy Kids. There are tons of books out there for boys and girls, but I'm seeing less available books for young boys out there and in the age of the XBox, this is VITAL. Girls are often more creative in thought and are drawn to the ability to read at this age, and it may be more dormant in boys so they really need to be able to find the perfect book, if they're not interested!