The Amazing Screw-On Head, on Sci-Fi
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Well, this is based on a one-shot comic from Dark Horse, which I'm afraid I've never read. Anyway, I first watched it on scifi.com, and then, 10 days later, watched it again when it premiered on Sci-Fi Channel. It could have become the pilot for a series, but unfortunately that didn't happen.

It's about a sort of robotic head, which, when necessary, screws onto any of various robotic bodies. His name is Screw-On Head (voiced by Paul Giamatti), and he works for President Lincoln, during the American Civil War. Can't really say anything about his origins as yet, though he does seem to have been around for well over a hundred years, at least. At some point in the past, he had a manservant (and best friend) named H.G. Manifold, who had a taste for ancient forbidden knowledge. And at some point, Manifold apparently turned himself into a zombie, albeit a very intelligent, articulate one. He calls himself Emperor Zombie, now (voiced by David Hyde Pierce), and is in the world domination business. Screw-On Head also has a dog named Mr. Dog, that seems now to be a sort of cross between zombie head and taxidermic body, but loyal to Head. Anyway, Head has had seven manservants since Manifold, all of whom have been killed by Zombie. Head doesn't want to get too close to his latest manservant, Mr. Groin, because of Manifold's betrayal... he can't really trust friends, anymore. Also, Head was once in love with a woman named Patience, who Zombie had turned into a vampire, so now she's Zombie's lover and servant, which is something else that, naturally, troubles Head.

Well, some ancient, apparently untranslatable text, which tells of someone named Gung the Magnificent, who used supernatural powers derived from a melon-sized jewel to nearly conquer the world in 9632 B.C., was stolen by Emperor Zombie. Lincoln sends Head to stop him from using the jewel to take over the world, himself. The jewel turns out to be a turnip with a small parallel universe inside. When opened, it releases a demigod, who Zombie says he wants to serve and advise on "dispensing horror in this modern military climate."

Well, I don't want to say how it ends. But I will say, there were some bits that I thought were kinda lame, but a lot of other bits that I thought were terribly clever and amusing. And I really wish it would have gotten picked up for series.