When two Action Girls are featured in the same film, frequently the tougher, more aggressive and less feminine character will die, despite being better equipped for the situation at hand.
One of the reasons is the belief that the femininity and sex appeal of a female character determines their usefulness as Love Interest or Fanservice or, in the most insulting cases, their reason to be in the story at all. It often suggests that this tough girl is actually a lesbian, which means she's not an option for a girlfriend. And you can't have two girls surviving when they're in the minority anyway, so the one who lives is the one who pleases the Shippers.
So ladies, if you pass aside your responsibilities as a maternal stereotype, or you're strong enough to get yourself involved in combat situations, even if you survive for a while you're not just violating the stereotypes of your gender... you're going to DIE! The moral? Stay at home.
A more charitable explanation would be that there's much more shock value in killing the tough, competent warrior; leaving the less warrior like one around thus increases suspense, since her survival isn't as assured, especially if Anyone Can Die. It's easier for an audience to feel fear if the Final Girl is less battle savvy and thus more vulnerable - a hardened Vasquez left alone wouldn't be as terrifying. The death of the Vasquez character is thus a form of The Worf Effect or Sacrificial Lion.
Writers will sometimes compensate by making the more attractive woman some sort of mysterious secret agent, thus relegating the Vasquez character to a Mook or Red Shirt by comparison. This may also be a byproduct of filmmakers' insistence that the female lead (who is likely to outlive her supporting cast in an action movie) be significantly more attractive than anyone else.
Compare Bury Your Gays, Faux Action Girl, Final Girl (the weakest and most innocent girl is the only one to live), Black Dude Dies First, The Worf Effect, Death by Pragmatism and Girly Bruiser (the most feminine female survives because she can kick ass in addition to being feminine) Overlaps with The World's Expert on Getting Killed, where the most qualified person in the whole cast, male or female, is killed early on and often with humiliating ease. Read more: Cracked.com: 5 Old-Timey Prejudices That Still Show Up in Every Movie
As a Death Trope, all Spoilers will be unmarked ahead. Beware.
Many times the Gundam protagonists fell in love with female Ace Pilots only to invoke the Love Hurts trope to Earth-shattering levels. However, this is not always the case. For example Shinn's first love is dress wearing, dance loving, sweet tempered Stella. She dies and his second love is his fellow soldier Lunamaria.
Giant Robo: The Day The Earth Stood Still: out of the two female members of Experts of Justice, Yoshi, the blue-skinned, muscular one dies halfway through the series, while the very feminine Ginrei survives to the last episode - and dies too.
In the Halo Legends mini movies, the survival rate of female Spartans is 0%.
In Martian Successor Nadesico, a bright female pilot is introduced as an replacement for Akito after he's unjustly blamed for a failed mission and removed from military service. Despite her having a spotless record as an experienced ace pilot, she quickly dies within the same episode during her first mission on the Nadesico.
In the original anime adaptation of Sailor Moon, the most tomboyish amongst the Inner Senshi, Sailor Jupiter, is the first to kick the bucket when they storm the Dark Kingdom towards the end of the first season.
In The Matrix, the gruff, spikey-headed Switch is killed, but Trinity, the love-interest, lives.
In The Matrix Revolutions, a female character named Charra with a crew-cut, a tanktop, and big ol' biceps is introduced right before the battle against the machines to help out Zee, who is trying to hold the line until her husband Link shows up. Guess what happens.
Holly from The Descent is a curious example. While she fits the "least feminine" part of the description, she was an impulsive and reckless amateur who obviously saw herself as an Action Girl but ended up getting herself injured through her carelessness. It was this that led to her getting killed off first. In the sequel, which has four Action Girls, the trained cave diver Cath is killed first, the average outdoor enthusiasts Juno and Sarah die last, and the cop Rios is left alive.
Carnosaur 2 features a tough female clearly modeled on Vasquez who is killed pretty gruesomely during the finale.
Justified in Lake Placid 3, where Yancy Butler's character takes down two giant crocodiles with a hunting knife after being both bitten and shot. Naturally, the injuries catch up with her.
The Action Girl is the first contestant killed in Slashers and just after she had killed one the eponymous psychos.
In Rambo: First Blood Part II this trope is averted. Co-Bau the machine gun Asian girl is shot dead by Captain Vinh, just after she rescues Rambo. Ironically, she was wearing a lovely red dress as part of the rescue (it was a Dirty Harriet) and looking very much like a Girly Girl.
Inverted in Leviathan which has two women on the team. Ditzy and more feminine Bowman dies (she kills herself when she finds out she has the parasite inside her) while the no-nonsense Olympic runner Williams is one of two survivors.
Sue Shiomi has fallen victim to this no less than five times:
In The Streetfighter, she portrays Nachi Shikenbaru, brother of Anti-Villain Junjo. She puts up some resistance against Terry Tsurugi when he attacks her brother Gijun for welching on him, as well as the pimps who swarm her after Terry prostitutes her through Mutaguchi. Also, in the end, she winds up coming closer to killing Terry than her brother (or Miss Yang) ever did... and she dies trying!
In The Streetfighter's Last Revenge, she portrays Kaho Huo Feng, a defector from Owada's gang and one of three women set up as potential love interests for Terry, the other two being Femme Fatale Aya Owada and her light feminine counterpart, telephone operator Kimiko Nakayama. Guess which two die.
In Golgo 13: Kowloon Assignment, she portrays an undercover policewoman who comes close to busting a drug operation before being killed in a shootout.
In Shogun's Ninja, she's a Chinese martial artist who's killed in a confrontation against Shogun's forces.
In Legend Of Eight Samurai, she's one of the eight dog brothers (who in this film is biologically female) who made a living as an assassin before she was discovered to be one of the eight. During the climactic final showdown, she's pitted against snake demon Yonosuke; they kill each other in combat.
Characteristic of vintage movies which often featured two female love interests; one passive and conventional and the other an action girl. The feisty girl usually ended up giving her life to save the hero's. One rare inversion of the rule was The Buccaneer in which Yul Brynner played Jean Lafitte. The passive blond wimped out and the tough girl got Yul.
In Smokin' Aces, there's Sharice Watters (Taraji P. Henson) the mentionably more badass and aggressive partner of Georgia Sykes (Alicia Keys), is gunned down by the FBI from behind while her more feminine counterpart is literally carried away to safety by a handsome "prince."
Cybil in Silent Hill suffers this fate, which is the opposite of the game's outcome (if you save her from being possessed).
Averted in You're Next. Erin, the Awesome Aussie daughter of a survivalist, is by far the most badass character in the film, male or female, and it's precisely this that makes her the Final Girl and turns the last third of the film into the most violent remake of Home Alone ever made.
Zig-zagged in Sharknado, in which tough barmaid Nova is swallowed by a shark while Fin's non-action ex-wife April escapes ingestion, only to have Fin cut open a shark and pull Nova out alive.
The two main Action Girl characters in the South Seas Treasure Game (Dream Park) are the sexy Acacia and the indefatigable Mary-Martha. Both acquit themselves well, but only one of them makes it to the end of the Game, and it's not the middle-aged, 4'1" veteran with the battleax. Inverted in the second sequel, The California Voodoo Game. Mary-Em makes it out alive and with a massive experience boost, while Acacia's character suffers Character Death, causing her to go through a Heroic BSOD.
Non-death example: the short story Assumption (scroll down) by Desmond Warzel. Belasco proves to be more effective in combat than the men or the unnamed female narrator, and is the only one seriously injured.
In the Shane Schofield series of novels by Matthew Reilly, there are two women who fit the Vasquez model. First there's Mother (short for motherfucker) who is over six-feet tall, shaven headed has a bionic leg and the ability to kill several men with her bare hands. Then there's Elizabeth 'Fox' Gant, who is slightly more ladylike, but has the short hair and the ass kicking ability. This trope is averted - but not for lack of the universe trying - up until the book Scarecrow, where Gant is beheaded by the asshole of the novel.
In The Two Princesses of Bamarre by Gail Carson Levine, tomboyish older sister Meryl is the one who becomes ill with the Gray Death, while delicate younger sister Addie survives and must carry on Meryl's mission.
Spy High. While the heroines are all Action Girls, it's Jennifer who is killed off in the third book, with Lori (the most stereotypically feminine) and Cally (the least focused and devoted to her training) who survive. Despite this, Jen's replacement Bex survives.
In the penultimate Animorphs book, pretty-yet-Rachel agrees to go on a suicide mission against the Yeerks and is ultimately killed. Fashion-challenged-Cassie not only survives that battle, but in the last book she stays on Earth while her male teammates are implied to die battling a Diabolus Ex Nihilo.
Inverted in the Venus Prime series. Despite being the lone Ambiguously BrownAction Girl on a team otherwise populated by white people, Jo Walsh survives through the end of the series. Meanwhile, the pretty white heroine, Sparta, disappears, and may actually have died to save all of reality from Nemo's meddling.
LOST: Ana Lucia (played by Michelle Rodriguez) and Juliet, Kate's only true competition for Alpha Female of the island or the affections of Jack and Sawyer.
Merlin: In the fourth series finale, Arthur has two women on his team: Guinevere and Isolde. Though their skill in combat varied wildly from episode to episode, Gwen was definitely the more passive and feminine of the two, whilst Isolde was tougher and had a more difficult lifestyle. Gwen makes it through the battle, Isolde is killed.
Power Rangers Lost Galaxy has an inversion. Due to Real Life Writes the Plot issues (the actress had to be written out after she was diagnosed with lukemia), the kind, friendly scientist girl was killed off while the athletic Jungle Princess remained. She was resurrected in the finale because her actress didn't die from her illness
Primeval: Inverted Trope, where tomboy Abby survived the series while the more feminine Claudia Brown and Sarah Page die.
Revolution: By the first season finale, there were two women connected to Miles Matheson named Nora Clayton and Rachel Matheson. Nora is is the tough, aggressive woman, while Rachel is the softer, more feminine woman. By the end of the episode, Nora dies and Rachel lives.
Star Trek: The Next Generation: Played straight with Natasha Yar. Notably, the character was originally designed as a Vasquez Expy. In this case it wasn't the writer's idea to kill off the character, but the actor's.
Cafe Nordo's Smoked! has Maddie Withers, a hard-drinking, masculinely dressed Lad-ette, who is gunned down in the final showdown, opposite Clara Still, the prim and proper saloon keeper.
In Red Faction 2, the team's sexual-innuendo-dropping stealth operative in a Spy Catsuit not only survives the game, but is your main ally for the 2nd half. The tough redhead sniper with an Amazonian build and butch haircut is the first of The Squad to die.
In Phantasy Star IV, Alys is built up as the best action girl. She is very popular in the game, because of her fighting ability and beauty. However, she dies off early and other action girls later reveal themselves.
Mass Effect 2: During the game's suicide run, it's far more likely for the tough, angry Jack to die than The Baroness Miranda. The time Jack is most likely to die is when she's standing in the least shielded portion of the ship while Miranda is in the most shielded portion.
Played with in Dragon Age: Origins – Awakening. Mhairi will always die, and of the two female companions who can make it to the end, both the tough, dagger-wielding Sigrun and the long-distance mage Velanna can die...but Sigrun is killed in a decisive way, while in Velanna's case, they Never Found the Body.
In the first Clock Tower game, playable character Jennifer's friends Ann and Laura have a chance of surviving to the end, depending on your actions. Her best friend, the tomboyish Lotte, has no such chance.
The Orion Conspiracy. Brooks, who is definitely the Vasquez in this game, gets killed off trying to stop Ward after he had gone berserk. LaPaz, who is easily more feminine compared to Brooks, survives.
In SAS: Zombie Assault 3 players who aren't logged in are given somewhat degrading names, one of which is Anonymous Vaskes.
Non-death example: in Total Drama Island,super-athletic but tempermental Eva is the second contestant, and the first girl, to be voted off. She is given a second chance at the season's halfway point but, having become even more angry, is voted off again in the same episode.