Some of these questions are deceptively hard!
1.) SAM (Okay, this one? Not so hard.)
2.) Zachariah. I think. Yeah. Just perfectly devious and snide and yet somehow...likeable? Though I thought Raphael, in his original vessel, was incredibly creepy. And Balthazar had the perfect blend of sexy and "I don't give a fuck about you hairless apes" of all of Kripke's holy host. All that being said, Castiel's entrance was incredible. Still, Zachariah. Coincidentally, my eldest son's name is Zakariah, but we named him before SPN was a glimmer in the network's eye.
3.) I gotta go Ruby. I just love her subversive nature.
4.) Alastair, oh wow. He was so damned nasty, and his chemistry with Dean was...just, oh wow. Azazel runs a close second, though.
5.) The 1st. I love the potential. But the 4th is very near and dear to my heart, too.
6.) Mystery Spot. I think it perfectly blends everything I love about SPN. But other faves are In My Time of Dying, Faith, Sacrifice, Clap Your Hands...
7.) Canon: probably Lisa/Dean and Sam/Ruby. Off-the-rails: Sam/Dean, Sam/Brady, Dean/Jo, Dean/Benny
8.) Do we really need to ask? I love Mark Pellegrino.
9.) This is a toughie. Gabriel, probably, because he seemed to have so much power and he used it so poorly. My runner-up may surprise folks: it's Abaddon. Not because I dislike the job the actres did, but because I wanted her to be scarier and tougher. I wanted her to be better-written, truly terrifying. But she came off like an arrogant thug.
10.) Kim Rhodes. Jody is awesome. But I dig Charles Malik Whitfield too. And Osric Chau. And Rob Benedict. And Rachel Minor. Sigh.
11.) Oh, crap. I've got to pick something? "Driver picks the music; shotgun shuts his cakehole." It's SO early-season Sam&Dean...when they were young and brash and hitting the road to find their dad and re-discovering each other. In later seasons, Sam's plaintive "So?" from Sacrifice sticks with me like an earworm. I can't unhear it. Then Dean's responding expression of absolute confusion and pain...well played, gentlemen. Well played.