I'll give it a shot...
This one is from the new Terminator series, not Firefly/Serenity, but you get the point. Summer Glau, a.k.a. River Tam from Firefly/Serenity and the new Terminatrix on Sarah Connor Chronicles.
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Then, also from Firefly/Serenity, Jewel Staite, a.k.a. Kaylee Frye. Also apparently plays a doctor on Stargate Atlantis.
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Next is Jeri Ryan, in the Trek Borg get-up...
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Then comes Alyssa Milano, a very-not-bad-looking witch from Charmed (there was a more "glamour shot" picture, but it didn't really look like her, so I picked this one)
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And from a picture that is old as I am, but still very babe-worthy, Supergirl Helen Slater
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Now Jane Seymour... I couldn't find a good picture of her from BSG, but here is a more recent one... and hot damn does she age well! She definitely does not look old enough to be my grandmother.
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And last, but not least, Kelly Hu, a.k.a Deathstrike from X-Men 2
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--edit: images not being images... changed them to links. Could a mod fix please?