Alexiidae is a family of beetles. It contains a single genus, Sphaerosoma, formerly included within the family Cerylonidae, with around 50 species which are native to the western Palearctic. Species of Sphaerosoma are very small, around 1 to 2 mm in length rounded beetles with clubbed antennae. They are fungivores, having been observed feeding on mushrooms, and have also been found in leaf litter and on decaying bark.

There has been considerable confusion regarding the type species and authorship of the genus; most older sources consider the author and species to be Sphaerosoma quercus Samouelle, 1819. That name is now considered to be a nomen nudum, and the valid name for Samouelle's species is Sphaerosoma piliferum (Müller, 1821). The type species is now considered to be Sphaerosoma quercus Stephens, 1832, which is itself a junior synonym of Sphaerosoma pilosum (Panzer, 1793). Alexiidae has been recovered as part of the superfamily Coccinelloidea as the sister group of Latridiidae.