Gluteus minimus is an extinct species of animal from the Late Devonian (Frasnian-Famennian) of Iowa that is the only species within the genus Gluteus. It was first collected in 1902, but only described in 1975 and the holotype is SUI 34978-91. Each animal appears as a bi-lobed lens up to 11 mm × 8 mm (0.43 in × 0.31 in), and almost all specimens share the same slight asymmetry. The species is of uncertain affinities, having been variously thought of as either a fish tooth, brachiopod, or an otolith.