Jim Rockford would sprinkle some garlic on his tacos and survive just fine. His trailer, on the other hand, would be trashed for the 1,000,001st time. His buddy Angel Martin would annoy the vampires so badly while hitting them up for money that he’d be toast.
Here’s a good Mars/Buffy crossover. Martian Manhunter by Mediancat
Well if we’re going to go too far afield…
Jayne would want to be changed into a Vampire because it would make him more badass.
Then he’d be destroyed by the first blast of sunlight through Firefly’s windows.
Or staked from behind by Kaylee.
Are we sure that the “sunlight” in that system has the same effect on vamps? Anyway, Firefly doesn’t really have many windows.
River would make a great slayer. And her brother is so pale…
The cast of *How I Met your Mother *will do surprisingly well, considering. Marshall, as we know, is freakin’ scary in a fight, and give Robin a six-pack and a sharpened hockey stick and she’ll be unstoppable. Lily and Barney may be useless in combat, but they’re both consummate schemers, which means that they’ll be able to put together an awesome tactical plan to defeat the vamps. Ted, though… Ted’s toast.
I realize it probably counts as “fantasy”—although it is a crime show—but I’m curious how Ned the pie-maker would fare against a couple neck-biters. If he touched them, would they come back to life?
Next on iCarly…
Vampires are totally cool!
I think Berta would kill all the vamps at the end, assuming she couldn’t just get away. She reads as badass coward.
Oh, yes, I forgot this.
But of course we all know that Lily is, in reality…
No. Foreman, Chase, Taub, and Thirteen would all die because they’d insist that the problem was lupus. House would eventually figure out it was vampirism and apply the appropriate remedy of garlic and wooden stakes.
The cast of Jersey Shore would probably take out the whole lot of vamps. You do NOT want to drink what’s swimming in those peoples’ blood streams. Snooki alone probably has enough STDs as to be classified as a biological weapon.
I was waiting for someone to suggest that.
Well, Edge and Christian are former vampires themselves, so I think they’d somehow manage. Maybe Matt Hardy, too.
And of course, Kane and Undertaker are in no danger.
BARNEY (runs into courthouse)" ANDY! The daed are walkin’! Otis is a vampire! I seen it!
ANDY : Now Barn, you know there ain’t no such things a vampires
AUNTI BEE: I don’t know Andy, there have been some funny goings on out at the old high school. I’d be careful if I were you.
ANDY: Hm. I still don’t thank it’s vampires, but we’ll wait till daylight, and have a good look around.
OPIE: ‘kin I come, Pa?
ANDY: Not this time, Opie, me an’ Barney will take care of it. You stay home and help Aunt Bee with the chores.
BARNEY: An’ I’ll bring my silver bullet!
HA! I killed the thread! I am VAN HELSING!
Mankind and Stone Cold would probably do OK too.
Mankind has done more harm to himself (plummeting from the top of the cage onto Gawd knows what pieces of splintered furniture are around), than any vamp could do to him.
Stone Cold would either squash them with his Zamboni, ram them with a fork lift, or just let them bite him and watch them fall over with alcohol poisoning from all the beer in his system 
I think Emerson would do quite well, though it would get confusing if his ex showed up.
The Magnum PI crew would fight the vampires while Higgins regaled them with stories of how he once fought vampires at a Hellmouth in Africa.