Odontophrynus monachus is a species of frog in the family Odontophrynidae. It is endemic to southeastern Brazil and only known from its type locality in the Serra da Canastra National Park (southwestern Minas Gerais state), in the headwaters of the São Francisco River, at around 1,350 m (4,430 ft) above sea level. The specific name monachus, derived from the Latin word for "monk", alludes to the type locality in the headwaters of the São Francisco River (="St. Francis River") and Francis of Assisi, known as a patron of the animals and of the environment.