Neytiri (Avatar): She's tough as carbon-reinforced nails, a crack hunter, and could crush you with her bare hands. Plus, she's been specifically engineered by James Cameron to make you want to sleep with her.
Mystique (X-Men): She's a shapeshifting spy and powerful leader against the world's anti-mutant forces, though her ethics are questionable. And let's not forget her statuesque appearance, one that demanded Rebecca Romijn play her in the movies.
Nocturne (Marvel): Mystique's granddaughter by an alternate reality Nightcrawler and Scarlet Witch, Nocturne has inherited her father's strange physiology (right down to the tail). On top of that, she shares Nightcrawler's acrobatic abilities and is a master contortionist.
Smurfette (The Smurfs): She's cute, and despite being created as an evil creature by Gargamel, manages to overcome her nature and become a happy Smurfing Smurf. Plus, the entire Smurf village is in love with her — although that may have more to do with her status as the sole female Smurf than her inherent appeal.
Talas (Enterprise): If you prefer a woman who's handy with a phaser, Talas might be your blue gal. The Andorian lieutenant isn't above using her feminine wiles to get the job done, but failing that, she's more than ready to fight.
Aayla Secura (Star Wars): Twi'lek's are considered especially beautiful by the various peoples of the galaxy far, far away — something that has left them both tragically vulnerable to slavery and powerful in the art of seduction. Aayla Secura pairs her appearance with great strength in the Force, rising to Jedi Master and fighting in the Clone Wars.
Zhaan (Farscape): Yes, she belongs to a species of sentient plants, but Zhaan is as hot-blooded as any being on the far side of the universe. She's a priestess and a revolutionary, as skilled with meditation as she is with making bombs. Just don't get on her bad side; Zhaan murdered the man she saw as a traitor to her people, even though he was her own lover.
Liara T'Soni (Mass Effect): Technically, the Asari are neither male nor female, though to humans they generally appear female and they can mate with any gender of any species. In Mass Effect , Liara is a wealth of information on Prothean technology, but one of the game's more memorable scenes is when she mates with the protagonist.
Namora (Exiles): In her home reality, the Atlantean Queen Namora is the most powerful person in the world, ruler of not just the waters but the entire planet. She may be haughty and superior, but it's hard to argue with a woman who, in her reality, took down the Avengers and the Fantastic Four.
Lyssa Drak (Green Lantern): If you have an affinity for supervillains in bondage gear, there's Lyssa Drak of the Sinestro Corps. In addition to battling the Green Lanterns, Lyssa is chained to the Book of Parallax, which holds the history of the Sinestro Corps and some freaky bits of lore.
Shadow Lass (DC): Like Lyssa Drak, Tasmia Mallor — descendent of L.E.G.I.O.N. members Lyrissa and Lydea Mallor — is a Talokian, which accounts for her blue skin. But Shadow Lass wields the ability to conjure darkness and fights as a superhero rather than as a villain.
Stella (Interstella 5555): She's the bass-playing member of the Crescendolls, an interstellar musical sensation that plays nothing but Daft Punk songs. The Crescendolls' talent is so great that an evil record exec wants to use them to take over Earth, and Stella's magnetism inspires a fan to pursue the Crescendolls to Earth and come to their rescue.
Icemaiden (DC): The same experiment that gave Sigrid Nansen her ice powers also turned her skin blue. Despite always looking frightfully, cold, she tends to wear that skimpy, low-cut outfit — though neither the men nor the women she's dated seem to complain.
Killer Frost (DC): Another DC lady with icy powers, Crystal Frost might not be the best person to strike up a relationship with; when her professor rejected her affections, she developed a hatred for all men (and it doesn't appear that she considered women an alternative). A better option might be her Killer Frost successor Louise Lincoln.
Diva Plavalaguna (The Fifth Element): The Diva is known for her striking beauty, grace, and heart-melting vocal abilities. But she's brave to boot, risking (and eventually sacrificing) her life to ensure the stones of the four Elements stay safe and out of the wrong hands.
Andromeda (Ascension): While caught up in the conflict between the warring Mineans and Dayaks, geneticist Andromeda Weaver is mystically imbued with blue skin and empathic abilities. She also develops an apparent preference for strappy, gravity-defying bits of clothing.
Sasa Lisi (Casanova): She's a time-traveling space spy and apparently the future lover of Casanova Quinn. She also comes with cowboy boots, a retro astronaut's helmet, and bonus detachable arms.
Fantomah (Jungle Comics(: You might have to get past her skull face, but the jungle-dwelling Fantomah is a living goddess and goes down in history as the first female superhero in comics.