Agnosphitys (/ˌæɡnoʊsˈfaɪtɪs/; "unknown begetter"; sometimes mistakenly called Agnostiphys or Agnosphytis) is a genus of dinosauriform that lived during the Late Triassic.

[1] The fissure fill at Avon, of which Agnosphitys was probably recovered from, was a sinkhole formed by the dissolution of Lower Carboniferous limestones.

The type species, Agnosphitys cromhallensis, was described by Nicholas Fraser, Kevin Padian, Gordon Walkden and A. L. M Davis in early 2002.

[3] The remains of Agnosphitys defied precise classification in the original description; the describers placed it outside Dinosauria using the definition of Dinosauria outlined by Padian and May (1995) and provided (on p. 80) the following diagnosis: "Well-defined brevis fossa on the ilium; semi-perforate acetabulum; `kidney-shaped' antitrochanter; well-developed posterior portion of the iliac blade; two sacral vertebrae; subrectangular deltopectoral crest that is 33 per cent of the length of the humerus; astragalus with a distinct ascending process and a prominent depression immediately posterior to the ascending process; in dorsal aspect an acute anteromedial corner on the astragalus.

[6] A large phylogenetic analysis of early dinosaurs and dinosauromorphs carried out by Matthew Baron, David Norman and Paul Barrett (2017) recovered Agnosphitys as a member of the clade Silesauridae.