Moustache de plume

Charlotte Brontë: People will have less respect for us as woman authors.
Emily Brontë: We should use male sounding pen names!
Charlotte Brontë: Brilliant!

Jane Eyre by Johnny Guns. Wuthering Heights by Bruce Punisher

—Hark! A Vagrant

There exists a belief that novels written by women, at least in certain genres, won't sell as well. Perhaps it's the stereotype that women tend to write domestic novels or "fluff" that have very narrow appeal. Perhaps it's because historically 90% of the works considered the great masterpieces of the literary canon are written by men. Perhaps it's because certain fandoms (Speculative Fiction for instance) are predominantly male and publishers assume these men won't take books by female authors seriously. Perhaps it's because the publishers themselves wouldn't even bother to read a book with a woman's name on it.

However, this has not stopped many women from writing and successfully publishing their works. They just have to pull small sleight of hand: conceal their gender. Since authors are usually not on film and therefore not seen, this can be done simply by adopting a pen name. Typically, female authors take one of three approaches.

Shortening their name to a series of initials which are gender ambiguous.
Adopting a completely male name to outright fool the public.
Adopting an ambiguous name in hopes that people will assume male.

Note: Sometimes highly successful female authors will create a Moustache De Plume if they are publishing a type of book well outside their normal material. For instance, Nora Roberts (a romance novelist) published mystery books under the pseudonym J.D. Robb.

Note 2: This trope is not for the likes of J.R.R. Tolkien, C.S. Lewis, or H.P. Lovecraft because they weren't using initials to conceal their genders.

There are, in fact, Spear Counterparts, as in the Romance Novel business.

Examples of Moustache de plume include:

Moustache de plume

Anime and Manga

Not an author, but an example nonetheless: In the original Japanese release of Gunsmith Cats, according to Word of God, female bounty hunter Rally Vincent's name is actually pronounced as Larry. It's hinted, at least in one page of the manga, that she took this name so that those seeking to hire a bounty hunter would think she was a man, and thus take her seriously.

Comic Books

In Iron Man Noir, Pepper Potts works as a pulp magazine writer under the pen name "Frank Finlay". When she applies for the position of Tony Stark's personal chronicler, describing the events of his exploits to be published in Marvels: A Magazine of Men's Adventure, she assures him it's a very common practice; Norman Brundage is her roommate Julie. Stark and his friend James Rhodes later share a chuckle over the fact that apparently some of his favorite writers wear skirts. At the end of the last issue, however, we see that her stories are now published under her real name - no doubt at Stark's insistence.

Literature

In Nim's Island, Alex Rover, an Indiana Jones type character who writes novels about his exciting adventures, is actually Alexandra Rover, neurotic female author.
In Darren Shan's third book of The Demonata, there is a movie producer named David A. Haym. Who is actually named Davida Haym.
In Little Women, the character Josephine attempts to get some of her writings published. She is unsuccessful until she uses the more masculine "Jo".

Live-Action TV

K.C. Hunter, Kira's counterpart in the Star Trek: Deep Space Nine Elseworld of 1950s science fiction writers, who's pretty clearly based on C. L. Moore (with Bashir's counterpart as Henry Kuttner). This is also likely a tribute to the aforementioned Dorothy Charlotte "D.C." Fontana, who was a 1960s Science Fiction writer for Star Trek, who originally started as Gene Rodenberry's secretary. She went by D.C. of course to avoid the stigma of being a female writer, and wrote some of the best-known episodes of the show, as well as the only episode of Star Trek: The Animated Series that was considered canon before Paramount finally allowed the rest of the series to be considered canon.
According to Warehouse 13, H. G. Wells was actually Helena Wells, and wasn't just making up about some of the inventions in her books.

Radio

An episode of the Canadian show Radio Active involved a guest speaker who was a woman who had been pretending to be a man to get into writing. It turned out to not be the woman pictured on the back of the book, but their English teacher, who explains that she had to to pretend to be an attractive woman pretending to be a man to be able to get anywhere in writing.

Web Comics

Web Comic example: This Casey and Andy strip.

Web Original

Homestar Runner - Strong Bad declared, in the sbemail "Secret identity", that he uses the name Cara Carabowditbowdit when writing articles for a popular women's magazine.

Real Life

J. K. Rowling, at the demand of a publisher (she doesn't really even have a middle name). Although by now few people mistake her for a guy.
K. A. Applegate
George Eliot. She adopted the name to ensure she would be taken seriously as an author, instead of being considered a writer of sappy Romantics (and sometimes plain ol' Romances), as most female authors of the time. She also penned the essay "Silly Novels by Lady Novelists," which hilariously criticizes the typical sappy romances of the time.
- Although her criticism is pointed more at the publishers than at the writers, as she realized that female writers were often not able to get the better sort of publishers to even read their books.
James Tiptree Jr. a.k.a. Alice Sheldon (also AKA Raccoona Sheldon)
George Sand
E. L. Konigsburg
S. E. Hinton
P. L. Travers
P. D. James
Hiromu Arakawa, author of the Fullmetal Alchemist manga, used the androgynous 'Hiromu' to spell her name instead of the markedly feminine Hiromi.
C. J. Cherryh, who also added a silent "h" to the end of her last name to differentiate herself from her SF artist brother David Cherry. There was also a tendency by less-than-attentive bookstore workers to put her books with the romances before the "h" was added.
Julian May (Her real name oddly enough, but she has also published under "Ian Thorne", "J. C. May" and "Lee N. Falconer".)
Robin Hobb (more Gender Blender Name than outright male but serves the same purpose).
John Sedges, aka Pearl S. Buck. And this was after she won the Pulitzer and Nobel Prizes.
Andre Norton
Inversion: Anne Rice, whose birth name was Howard Allen O'Brien. Though that's more to do with a wacky name her parents gave her. Although she has also published books under the name A. N. Roquelaure.
- Rice used the Roquelaure pseudonym for her erotic novels, in order to distance them from her supernatural books. Kind of pointless, though, since current editions of the naughty books have both names right on the cover.
S. D. Tower
Henry Handel Richardson (real name: Ethel Florence Lindsay Richardson) adopted a male name because of the difficulties 19th century women faced in getting published.
Mary Shelley at one point published Frankenstein anonymously with her husband's name on the preface, which he wrote for her. This gave the impression Percy Bysshe Shelley wrote the whole thing. The initial publishing had no attribution at all.
All the Brontë sisters originally published their stories under male pseudonyms. (Currer, Ellis, and Acton Bell, for Charlotte, Emily, and Anne.) This is sent up in Cold Comfort Farm where the male intellectual Mr. "Maybug" Mayerberg, indignant that so many of England's greatest novels were written by girlies that he writes a thesis claiming that they were all drunks and druggies and their brother Branwell (who was the drunk and druggie of the family in real life) wrote all their stories for them.
Ursula K. Le Guin's first publisher had her credited as U. Le Guin. She got rather upset when she realised that her middle initial (K. for Kroeber) was omitted. Add to that that female SF authors were rare in the 1960s. She changed to the current version of her name shortly afterwards.
C. L. (Catherine Lucille) Moore, co-author and wife of Henry Kuttner. Significant number of works billed as Kuttner's were actually written by Moore, because they noticed stories sold better under his (pen)name(s).
Holy Bibble. Don't be fooled by the avatars of the two authors, they are two girls (and if you look at each avatar closely, there's a girl hidden behind a boy)
D. C. (Dorothy Catherine) Fontana, writer of some of Star Trek's best-loved episodes.
K. J. Parker Possibly: Parker's gender is not known.
C. S. Friedman changed to Celia Friedman in her most recent works and reeditions.
J. V. Jones
Karen Blixen published her works (most famously Out of Africa) under the pen name of Isak Dinesen (Dinesen was her maiden name).
Rob Thurman is really a Robyn, female.
Nelle Harper Lee. Really interesting, since To Kill a Mockingbird is both autobiographical and plainly from a girl's perspective.
Stella Miles Franklin
J. T. Leroy, although this was an entire invented persona rather than simply an attempt to conceal her gender alone.
R. M. Meluch
The writer of the popular ambulance control centre blog Nee Naw admitted they were using pseudonyms for anonymity reasons. Still, it was a shock when 'Mike Myers' revealed that he was actually a 'Suzi Brent'.
J. O. Jeppson, later to use her married name, Janet Asimov.
D. C. (Dana Claire) Simpson, creator of Ozy and Millie. Some justification for this as Simpson is transsexual and initially self-published under her birth name of David Craig Simpson.
"The" poet Michael Field (actually two women, Katherine Harris Bradley and Edith Emma Cooper).
Short-story author George Egerton (Mary Chavelita Dunne Bright).
Novelist and playwright John Oliver Hobbes (Pearl S. Craigie).
Science fiction novelist Ann C. Crispin's best-known works, the Han Solo Trilogy from the Star Wars Expanded Universe, were published as A. C. Crispin, though the "About The Author" section clearly had her as Ann C. Crispin.
Ellis Peters was really Edith Pargeter. She also published less-famous mystery novels as Peter Benedict, Jolyon Carr and John Redfern.
Neither of Chris Moriarty's books have any sort of identifying pronouns in either the endorsement blurbs or the author bio. She has confirmed that that omission, along with the ambiguous first name, was a deliberate decision by the editors.
Several authors of Star Trek fiction—in addition to D. C. Fontana and A. C. Crispin mentioned above, there are J. A. Lawrence (Judith), M. S. Murdock (Melinda), J. M. Dillard (Jeanne), V. E. Mitchell (Vicki), L. A. Graf (a joint pseudonym for two women, Karen Rose Cercone and Julia Ecklar), S. D. Perry (Stephani), and S. N. Lewitt (Shariann).
E. M. (Edith Maude) Hull, author of The Sheik.
E. Nesbit
Katsura Hoshino, creator of D.Gray-man, was thought of being male until 2008, when this cute girl with short hair appeared in a Convention. For that moment people had started to be suspicious about the gender, but it still got surprise.
I. J. Parker, creator of Sugawara Akitada.
English historian C. V. Wedgwood (Cicely Veronica) Wedgwood.

Inversions: Womb de Plume

Anime and Manga

In the anime Ef a Tale of Memories, Hirono Hiro, 17 year-old male who is a professional mangaka, writes under the pen name Shindou Nagi, claiming to be female. Given that his work is Shoujo, it's understandable.
In Otomen Tachibana Juuta writes sparkly romance shoujo manga under the penname Sachihana Jewel, and refuses to disclose his real identity even though the manga is hugely popular, because he's afraid readers wouldn't take well to their shoujo manga being written by a man. He goes as far as crossdressing whenever he needs to appear as Sachihana.
- There's also his favorite mangaka, Mira-sensei (short for "Mirage") who dresses, speaks and behaves like a classic '70s shoujo manga character, for the same reason as Juuta. His motto is "Because we're professionals!"
In Himitsu no Hanazono the four brothers work under one female name to publish their shoujo manga.

Fan Works

In the Harry Potter fic series known as the Dangerverse, Sirius Valentine Black publishes romance novels under the pen name Valentina Jett.

Literature

Henry Fitzroy of the Blood Books writes romances under the psuedonym "Elizabeth Fitzroy." Since he's the bastard son of Henry the 8th, he thinks that's pretty amusing.
Artemis Fowl - Artemis, at least according to his inner monologue, has been writing romance novels under the name Violet Tsirblou since age ten, if not longer. Which is ironic considering that Artemis is usually girl's name. However, he doesn't want his real name associated with them...
In Joan Hess's Strangled Prose, Douglas Twiller not only writes steamy romance novels under the pseudonym "Azalea Twilight", but has his wife pose as Azalea for public appearances. This is as much a way to shield his reputation as a professor of literature as to guard his gender.
Robert Heinlein has a fictional example using his own real example. Colin Campbell of The Cat Who Walks Through Walls is a professional writer doing romance under a female pen name.

Live-Action TV

In the Blackadder episode "Ink and Incapability", the protagonist writes Edmund: A Butler's Tale under the name Gertrude Perkins, because everyone wants books by women nowadays. He claims that Ann Radcliffe, Jane Austen and Dorothy Wordsworth are all men, Austen being a "a huge Yorkshireman with a beard like a rhododendron bush". "James Boswell is the only real woman writing at the moment, and that's just because she wants to get inside Johnson's britches."
On Just Shoot Me, Dennis Finch writes the advice column for Blush under the name Miss Pretty.

Real Life

This sort of thing generally happens to male novelists who want to write romance novels.
- Gardner Fox, the creator of The Flash, the Justice Society of America, and the Justice League of America, wrote romance novels under the pen name Lynna Cooper.
- Peter O'Donnell, the creator of Modesty Blaise, wrote romance novels as Madeleine Brent.
- Romance novelist Leigh Greenwood is male. Greenwood actually uses his real name; however, it certainly helps that the spelling "Leigh" is traditionally thought of as feminine. On the other hand, film director Howard Hawks was very surprised to discover that the science-fiction author Leigh Brackett, whom he had hired to co-write the screenplay for The Big Sleep, was a woman.
Almost all of Yoshiki Hayashi's more heavily sexual lyrics are under the name "Hitomi Shiratori." Specifically, "Stab Me In The Back," "Orgasm," and "Standing Sex" are all credited to "her."
There are also married couples who publish under the wife's name or a female pseudonym.
Michael Hardcastle wrote books about football for boys. He also wrote books for girls about horses, but under a woman's name so they wouldn't think the books were aimed at boys.
Robert Heinlein wrote romance and true confession stories under a number of feminine pseudonyms, sometimes using his wife Virginia's name for the purpose.
The young children's author Martin Waddell wrote his earlier YA books, which often have female protagonists, under the name Catherine Sefton. He now writes YA under his own name as well.
L. Frank Baum wrote romances under a female pseudonym.
The Cat in the Stacks armchair/amateur sleuth mystery series is written by Dean James under the pseudonym Miranda James.
Both male and female writers wrote Nancy Drew and The Dana Girls novels under the pseudonym Carolyn Keene.
Accidental example: One of Terry Pratchett's early books, Equal Rites, was adapted for BBC Radio's Woman's Hour. Given that the book centres on feminism, many listeners assumed the author was in fact a woman named "Terri Pratchett".
The poet Fiona MacLeod (William Sharp).
Tim Pratt, the author of The Strange Adventures of Rangergirl, wrote his Marla Mason fantasy series as T.A. Pratt.
Dan Brown's first book was a toilet volume called 187 Men To Avoid, written under the name Danielle Brown.
Zig Zagged with Michael Grant, K. A. Applegate's husband, wrote several of the Animorphs books under his wife's (pen)name. Which means he was writing books under her Moustache De Plume.
Michael Thomas Ford wrote the Circle of Three series as Isobel Bird. He's said it was because he was trying to keep his YA work and his adult work separate, but the fact that the series is about three teenage girls studying the very female-oriented religion of Wicca might have had something to do with it.
Joyce Kilmer, author of Trees, was a man. His full name was Alfred Joyce Kilmer.
Benjamin Franklin's first foray into newspaper writing was done under the pseudonym, and indeed the persona, of the fictional widow "Silence Dogood". In penning his letters as Silence, he wasn't so much hiding his gender as concealing the fact that he was a sixteen-year-old kid.
Dan Ross, another romance novelist, used several female pseudonyms, most notably (for tropers) that of Marilyn Ross, under which he wrote novels for the Dark Shadows franchise.
To get some money, thriller and comic writer Mike Carroll wrote a few chick-lit romance novels under the name Jaye Carroll.