4. 'Castle': Castle and Beckett (Season 4, Episode 23)
After four long seasons of sexual tension and a couple of faux lip-locks (look, 1940s doppelgangers! Quick, distract that security guard!), "Caskett" shippers got what they wanted: a bona fide kiss. And what a kiss it was. After showing up on Castle’s doorstep soaking wet after a fight, Beckett made the bold move, which quickly devolved into a full-blown make-out session. But the best part? The tender moment where the crime-solving duo held hands as the screen faded to black, closing out the Season-Four finale. Like Mulder and Scully and Bones and Booth before them, it's proving to be a relationship that keeps on giving.