Bride and Switch

A young couple are all ready for the big day. Only the bride isn't who the groom thinks she is. Maybe it's an Arranged Marriage, and someone else is impersonating the bride he's never seen. Maybe a shapeshifting alien has taken her place. Or maybe she's simply using a wedding veil as a convenient disguise.

The wedding rarely if ever goes through, with the real bride (or groom, in gender-flipped examples) bursting in at the last moment. Very occasionally, the groom may fall in love with the "fake" bride and marry her for real. Legal trickery may establish that the false bride can be treated as the true bride's proxy, and so he really did marry the true bride. In many Fairy Tales, the false bride is executed for her attack on the true bride—sometimes substantially after the wedding took place—as a complication in the heroine's Rags to Royalty rise. (This is often a case of Sibling Triangle.)

Note that many of these rules are reversed if it's a villain who's trying to marry our plucky heroine for devious and evil reasons. In these cases, the villain often does end up married to the fake bride, usually for the sake of invoking some comedic comeuppance.

Compare Bed Trick, which is the less G-Rated version of this trope.

Examples of Bride and Switch include:

Ballads

In the Child Ballad The Lord of Lorn, the young lord has his position stolen by a treacherous servant. Fortunately, although he promised to never tell any human, he can tell a horse.

Comic Books

Sub-Mariner #36 (1970s): Llyra tricks the Sub-Mariner into marrying her instead of Dorma, who's been kidnapped. It turns out that Atlantean marriage laws let you use a substitute at your wedding—he is considered to have married Dorma anyway. The official had put Dorma's name down on the wedding document, which is what made Llyra just a stand-in.
In Fantastic Four #300, Johnny Storm marries Alicia Masters, but a later Retcon made the Alicia he married really a Skrull shapeshifter.

Fairy Tales

The Goose Girl is actually the princess, whose servant has usurped her place as the bride.
In The Two Cakes, the heroine is pushed overboard so that her sister can take her place.
In The White Bride and the Black One, the Wicked Stepmother pushes the heroine out of the coach into the water to substitute her own child.
In Maiden Bright-eye the stepsister pushes the heroine overboard to take her place as the king's bride.
In Bushy Bride, the heroine is tricked into jumping overboard so her stepsister can take her place.
In The Sharp Grey Sheep, the stepsister cut off part of her foot to fit the shoe.
In The Brothers Grimm's Ashenputtal, the stepsisters cut off part of their feet to fit the shoe.
In The Wonderful Birch, the witch whittles her daughter into shape to wear the heroine's things.
In Maid Maleen, the princess, working as Scullery Maid is asked to substitute herself for the bride by the bride herself, who either wants to hide her ugliness or her pregnancy. Alas for the bride, this means that Maid Maleen can reveal that she's the prince's old love, not actually dead.

Film -- Animated

Played for Laughs during a montage in the fourth Shrek installment, in which the eponymous ogre dresses as a veiled bride at a man's wedding just to freak him out.

Film -- Live-Action

The George of the Jungle movie features this trope at the climax, with Lyle trying to forcibly marry Ursula when they enter a dark tunnel. Upon exiting the tunnel he learns that he actually married an amorous gorilla instead.
In the 1934 version of Babes in Toyland, Little Bo Peep agrees to marry Barnaby so that he'll settle the mortgage on Mother Peep's shoe house. However, he's tricked into marrying Stanley Dum, who had dressed up as the bride and hidden his face with the veil.
At the end of Coming to America, Prince Akeem returns home to the Arranged Marriage he left in the first place to escape. When he lifts his bride-to-be's veil at the start of the ceremony, it's not his arranged bride, but Lisa, the love interest he'd left behind in New York.

Literature

In Book of a Thousand Days by Shannon Hale, Lady Saren forces her maid, Dashti, to act as her when interacting with her fiancé, Khan Tegus. This goes so far as to go through the betrothal ceremony, and Saren plans to have her go through the marriage ceremony as well. She does, but as herself, and not Saren.
In the Chivalric Romance Roswall and Lillian, Roswall is forced by a servant to allow the servant to pass himself off as Roswall and never reveal the truth to any human. The servant uses this to woo a princess. But some magical knights reveal the truth.
Grace Livingstone Hill must have loved this trope, because she used it in two separate novels: Exit Betty (Betty is nearly tricked into marrying the cousin she hates instead of the one she tolerates) and Dawn of the Morning (where the substitute husband is far better than the original).
Towards the end of Sheri S. Tepper's The Companions, main character Jewel does this to her ex-husband, who is still infatuated with her. She has the identity of the fake bride concealed by telling him that veiling the bride until the wedding night is a tradition of the planet she now lives on. On the wedding night itself, she uses scent-language shenanigans to de-infatuate him with herself and re-infatuate him with his new bride. He doesn't mind, but his mother is not amused. That is to say, she opens fire.
In the Dresden Files short story "Something Borrowed", this trope is invoked when Jenny Greenteeth takes the bride's place at Georgia and Billy's wedding.

Live Action TV

One of the many Gambit Pileups in Allo Allo had Rene due to marry the leader of the Communist resistance, who was replaced by his waitress Yvette, who was then replaced by his wife Edith (although Rene at that point was playing his own twin brother). The vicar had also been secretly replaced by Officer Crabtree, so we aren't sure exactly whether anyone had managed to get married.
One time on The Andy Griffith Show, Ernest T. Bass tried to steal a bride away from her wedding but it turned out to be Barney Fife under the veil.

Ernest T: I'm a little mean, but I make up for it by bein' real healthy. Say you'll be mine. Say you'll be my beloved!
Barney: (lifts veil) I wouldn't marry you if you were the last man on earth!

In Power Rangers RPM, the good guys do this, the bride to be Summer, the Yellow Ranger is replaced by Dr. K after the bride realises that not only does she really not want to go through with her Arranged Marriage but that she needs a diversion because the enemy has attacked the wedding.
- This happens again in Power Rangers Samurai, when Mia and Emily pull a Batman Gambit on Dayu, who has been kidnapping brides from their weddings.
On Charmed, Paige's old friend/on-and-off boyfriend is getting married, and having been turned insane by some sort of magic (as usual), she winds up trying to get rid of the bride and turns herself into a copy. Thankfully Leo rescues the real bride and sets everything straight just in time.
There was a Lifetime Movie of the Week called What Matters Most. At the end of the movie, there is a wedding. The viewers are led to believe that the boy is going to marry an Alpha Bitch, per his father's wishes. However, when the bride arrives at the altar, she is revealed to be his High School Sweetheart who is also the mother of his child. The couple marries after the boy's father reluctanly gives his blessing to the young family. Just before the credits roll, his best friend narrates in a voice-over that the Alpha Bitch and her Girl Posse along with the boy's mother arranged the whole thing.

Religion and Mythology

The Bible gives us the story of Jacob, who labored for seven years without pay for the right to marry the woman he loved, Rachel. The next morning he discovered that his bride was Rachel's older sister Leah, and that the deception was orchestrated by their father Laban because he thought it was improper for the younger daughter to be married before the elder. He did end up with Rachel, after working another seven years for her.
- This, incidentally, is supposed to be the origin of the whole "lifting the veil" tradition. (Presumably Leah's wasn't see-through.)
- The retelling of this story in The Red Tent suggests that this was a deliberate Bride and Switch on the part of the two daughters.
  - The Talmud, IIRC, says that Rachel suspected Laban might try this and arranged for her and Jacob to give each other subtle cues at the altar so he would know whom he was really marrying. However, right before the wedding Rachel realized that Leah would be humiliated if Jacob called the wedding off and revealed the signs to her.
In Norse Mythology, the giant Thrymr steals Mjollnir in order to demand Freya as his bride; after Freya refuses, Loki comes up with the cunning plan to dress Thor in women's clothing and a veil. It works, albeit with some fast talking from Loki as Bridesmaid. The giants hand the "bride" Mjollnir, and Thor throws off his veil and kills them all.

Theater

The Ugly Duckling by A.A. Milne (not to be confused with the fairy tale by Hans Christian Andersen) has a double version of this. The beautiful lady-in-waiting is recruited to woo the visiting prince, but the intended bride, the plain princess, will be married in heavy veils. Meanwhile, the prince plots the same thing with his dashing footman and a suit of ceremonial armor. Fortunately, the prince and princess meet on their own and fall in love.
Inverted in Much Ado About Nothing. Claudio has been led to believe that Hero has died of grief over his accusations of sluttery, and to atone he has promised to marry her cousin sight unseen. But it turns out that it really is Hero.

Video Games

Done in three of the four prologues of Aveyond: The Lost Orb, where Lydia magically disguises herself as the girl Edward intends to marry. Unfortunately for him and his real bride, Mel reveals the deception too late, and the marriage is considered legally binding.
Near the end of The Secret of Monkey Island, LeChuck is about to marry governor Elaine Marley when pirate-wannabe Guybrush Threepwood burst into church to stop the wedding. Unbeknowst to both villain and hero, Elaine escaped much earlier and the bride is actually two monkeys in a dress armed with a ghost-destroying seltzer bottle, ready to strike at the right moment. Guybrush naturally manages to mess that up.

Web Comics

In Erstwhile, the bride orders Maid Maleen to take her place.

Western Animation

An episode of Dudley Do-Right had him pull this trick on Snidely Whiplash, who was trying to marry Nell, by replacing Nell with his horse. (It worked!)
On Adventure Time, Finn and Jake keep the Ice King from forcing a princess to marry him by switching her with Jake's finger just before ~~the kiss~~ the beard-touching makes it official. Unsurprisingly, the marriage doesn't last long.
On Space Stars, in the Teen Force short "Trojan Teen Force", Uglor was about to marry Princess Keena, but it was actually Moleculad in disguise.
In the second season finale of My Little Pony Friendship Is Magic, the bride-to-be, Princess Cadence, is replaced by a shape-shifting imposter.
In one episode of The Simpsons, “Homer and Lisa Exchange Cross Words,” Homer gets a job helping people break up. For one of his assignments, he disguises himself as the bride at a wedding and lets the groom down easy.
- In their retelling of the adventures of Tom Sawyer and Huckleberry Finn, Huck (Nelson) is forced to marry Becky (Lisa) at gun point. Huck escapes his dire situation by substituting a pig in a suit for himself.