In modern times it is most common in romance novels, especially historicals in which a heroine often spends part of the book disguised as a boy, the hero sometimes falling for her while thinking she is a boy. Occasionally a hero will cross-dress, using a female disguise to avoid recognition or to gain access to someplace where he would never be able to go as a man.
However, the trope isn’t just found in romances, as may be seen in the list below, in which I recommend stories with a variety of cross-dressing characters. Unfortunately I was only able to dredge up from the depths of my memory two book-length stories I had read in which men cross-dress, so this is mostly a list of women dressed as men.
- Ghost Riders by Sharyn McCrumb. One of the interwoven stories in this novel is the more or less true story of Malinda Blalock, who disguised herself as a man in order to go with her husband into the army to fight in the American civil war.
- The Masqueraders by Georgette Heyer. About twins of the opposite sex who have for a long time masqueraded as the other sex and become very good at it. A bit far-fetched but good fun.
- The Corinthian by Georgette Heyer, in which the young heroine is able to fool everyone but the hero into thinking she is a boy.
- These Old Shades by Georgette Heyer, in which the heroine spends a considerable part of the book disguised as a boy.
- Twelfth Night by William Shakespeare. The cross-dressing plot in this comedy play verges on the ridiculous as people keep confusing Viola, the cross-dressing sister, with her undisguised twin brother, but Shakespeare’s brilliant plotting and way with words makes it work.
- Cue for Treason by Geoffrey Trease. In this YA historical novel a girl who is running away from an arranged marriage disguises herself as a boy and in a girl-as boy-as girl twist ends up playing all the female leads for the troupe of actors amongst whom whom she has hidden. I can’t remember - as it has been a while since I read it - if she ever plays Viola, in which case she would be a cross-dressing cross-dresser.
- The Merchant of Venice by William Shakespeare, in which the heroine Portia disguises herself as a man in order to defend her lover Antonio in court.
- The Two Towers, the middle book in The Lord of the Rings trilogy by J.R.R. Tolkien, in which Éowyn, the brave female warrior, disguises herself as a man in order to be able to fight the enemies of her people. This is actually an easy disguise, as she simply has to keep down the visor of her helmet and no-one is any the wiser.
- My Lady Notorious by Jo Beverley. While the heroine does briefly cross-dress - not very successfully as the hero immediately sees through the disguise - the hero has much better success when he dresses up as a woman and pretends to be her sister’s chaperone.
- Monstrous Regiment by Terry Pratchett is a brilliant parody of this trope. In the beginning Polly Perks cuts her hair short and disguises herself as a boy in order to join the army so she can find her brother, but at the end there are so may cross-dressers and cross-dressing cross-dressers that you don’t know where to begin counting.
- The Triumph of Love by Pierre de Marivaux. Another play, in which a princess disguises her self as a man and infiltrates the home of her greatest enemy in order to right a wrong. Although in the movie version the male disguise is laughably easy to see through, it’s still good fun to watch.
- Jingo by Terry Pratchett, in which corporal Nobbs cross-dresses as an unimaginably ugly woman, with very funny results.