Nycteribiidae is a family of the true fly superfamily Hippoboscoidea. Together with their close relatives the Streblidae, they are known as "bat flies". As the latter do not seem to be a monophyletic group, it is conceivable that bat flies cannot be united into a single family.

They are flattened, spiderlike flies without eyes or wings, and as such bear very little resemblance to other Dipterans. These flies are seldom encountered by general collectors, as they rarely leave the body of their hosts. Female bat flies often must leave their hosts to breed and lay eggs, however, they will not leave their bats immediate habitat. Both males and females take blood meals, thus qualifying as parasites. Most species are highly host-specific. The family is primarily found in the Old World tropics; a few of the 274 known species occur in the Neotropics and Europe.

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