Meizonyx is an extinct genus of megalonychid ground sloth from the Pleistocene of El Salvador and southern Mexico. The type and only species, Meizonyx salvadorensis, was described in 1985 from a mandible found in Barranca del Sisimico and other remains found at Rio Tomayate in El Salvador considered to be Middle Pleistocene in age. Later, in 2021, two partial skeletons were described from Late Pleistocene aged deposits in Sistema Huautla cave in, Oxaca, Mexico, with one of these dating to around 12,562 ± 130 years Before Present. It is considered closely related to Xibalbaonyx. It is thought to be comparable or somewhat greater in size than Megalonyx jeffersonii. It inhabited relatively mountainous areas.