Mazothairos (from Mazo, derived from its location of Mazon Creek and θαιρός, thairos, meaning 'hinge' in Greek) is an extinct genus of very large insect from the Carboniferous period. It was a member of the order Palaeodictyoptera. Although it is only known from very fragmentary remains it is estimated to have had a wingspan of about 56 centimeters (22 in), making it one of the largest-known insects, only being rivaled in size by the largest members of the order Meganisoptera, such as Meganeura and Meganeuropsis.