Comedies about vampires have traditionally sucked, but though this New Zealand mockumentary from the makers of “Flight on the Conchords” suffers a bit from tired blood in its final stages, overall it manages to be mildly diverting and even somewhat touching, which given the genre is quite an accomplishment.

The setup finds four vampires sharing a house in Wellington, and inviting a camera crew to record their undead lives, accompanied by explanatory commentary. The chattiest of the bunch is Viago (Taika Waititi), a dandy 379 years old who tries to keep the place tidy despite his roommates’ lack of decorum and his own occasional accident in hitting the wrong vein of a guest and causing a mess. Then there’s Vladislav (Jemaine Clement), also called Vlad the Poker, who’s 862 and of rather more gory taste. The other two roomies are at opposite ends of the age spectrum. The oldest by far at 8,000 years is Petyr (Ben Fransham), who resembles Nosferatu, while relative newcomer Deacon (Jonathan Brugh) is a mere 183.

The picture takes amiable aim at the inconveniences caused by all the usual elements of vampire mythology in a modern setting. It’s difficult to primp oneself up for a night on the town, Viago explains, when you can’t see your reflection in a mirror; and getting into a club is a problem when you can’t enter until you’ve been invited. There was also a problem in his transport to New Zealand, Viago explains, since his amanuensis didn’t pay proper shipping, leaving the voyage to take so long that his beloved, tired of waiting, got married to another; he still pines over her. (The episode has a further twist when Viago Skypes the man, who complains to his “master,” Renfield style, that he hasn’t been turned into a vampire as promised, and now, at ninety, would be too old to enjoy it.)

Deacon, moreover, still frets over the timer he spent as a member of Hitler’s vampire army, and is also irritated when Petyr puts the bite on Nick (Cori Gonzalez-Macuer) and turns the guy rather than killing him. Nick turns out to be a real pest, blathering about his undead status to anybody who will listen and violating house rules by bringing human Stu (Stu Rutherford) over—who nonetheless turns out to be a nice, helpful fellow. A few other regular folk don’t seem to mind their neighbors’ conditions, either, although the local community of werewolves can be difficult, even though they’re basically fine creatures who try as hard as they can not to give in to their animalistic side. And of course when our resident vampires invite ordinary folk over to dine, it can turn into a very different sort of meal.

Vlad’s big problem has to do with a battle he once had with a figure he calls the Beast, whose identity will be revealed in a big masquerade ball for all Wellington’s creatures of the dark—zombies as well as vampires—toward the close. By that time, to tell the truth, “What We Do in the Shadows” is beginning to run out of steam; even at a mere 87 minutes, it feels like a sketch that’s overstaying its welcome, especially since the mockumentary format can make up for the threadbare look of things only so long (though actually some of the makeup and transformation effects are surprisingly good).

But horror movie fans shouldn’t mind the flaws overmuch. The movie is a send-up of the vampire mythos that’s affectionate and genial, and for the most part it makes for a tasty little meal—probably the best thing of its kind since the far more elaborate, and terribly underrated, Roman Polanski picture of 1967, “The Fearless Vampire Killers or: Pardon Me, But Your Teeth Are in My Neck.”