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troperville

Her wardrobe consists of pure white gowns that are somehow both full-length and yet split almost to the crotch. And I'm not convinced she wears a bra.
— Towny, a member of The Doctor Who Forum, discussing Servalan from Blake's 7

A female character who provides a significant amount of Fanservice (generally for males), ranging from simple revealing of cleavage, midriff, shoulders or le gs, to shots of her curves, hips or derriere (even when covered).

Her clothing is mainly there to accentuate her figure. Her wardrobe mainstays are bikinis/swimsuits, lingerie, fishnets, stockings, garters, Dangerously Short Skirts, equally short shorts, boots, and low-cut dresses and shirts. Alternatively, she might be covered from head to toe, thus showing no skin at all, but her costume will be tight and stretchy enough to show her bust and the outline of her hips. Bonus points if she's The Tease.

There are several types of Ms. Fanservice:

A Fanservice Extra provides eye candy, but never appeared before the moment of such eye candy and never appears again. Compare Best Known For The Fanservice.
An Innocent Fanservice Girl has no qualms about strutting her stuff in front of others; she doesn't see a problem in it. This can range from flat-out nudity to posing in skimpy outfits when asked.
A Reluctant Fanservice Girl prefers to dress modestly, but the universe conspires to subject her into providing fanservice anyway, which she takes issue with.
A Shameless Fanservice Girl doesn't care if you're uncomfortable with her lack of clothes or penchant for skimpy outfits. She'll bare her figure anyway.

Either way, the camera seems to have the hots for her, and the viewing audience is expected to feel the same way. The real trick is to make it so that being eye candy doesn't make her a Flat Character. Besides, being "flat" usually doesn't fit this type of character.

Please note that there is no requirement to actually be single to fit into this trope. Many of these characters are married. For the Spear Counterpart, see Mr. Fanservice. If she also sleeps with most of the crew, she either Really Gets Around or is a Good Bad Girl. Subjected to multiple Double Standard tropes, especially if she actually gets a nice dose of Character Development or Hidden Depths aside of her hot looks, and yet the fandom refuses to see them.

Compare Hello, Nurse!, and contrast the Token Wholesome. See also Memetic Sex God.