26 True (Fictional) Lovers: Pop Culture's Best Couples

GAIUS BALTAR AND NUMBER SIX
Battlestar Galactica
Most great love stories don't begin with a scientist selling out his entire species to a seductive undercover agent who ultimately lays waste to his planet. But nothing's typical about the relationship between Battlestar Galactica's flawed, half-mad Dr. Gaius Baltar (James Callis) and slinky, enigmatic Number Six (Tricia Helfer). For starters, he's human, she's a Cylon. And then, of course, there's the way Six randomly appears to Baltar — guiding him, admonishing him, getting busy with him — in a way that no one else can see her. Is she an apparition? A figment of his addled mind? Really good at disguising herself? It's never quite clear, but the Baltar-Six pas de deux is the sexy, species-crossing relationship at the heart of this sci-fi masterpiece. —Michael Slezak