Tyrannoscelio, new genus is described from the Neotropics type species: T. genieri, new species. The position of the genus within the Scelioninae is unclear, but the presence of a well-developed skaphion suggests a relationship with Psilanteridini, Thoronini, or Parascelionini. Tyrannoscelio is characterized by a strongly produced frontal ledge and enormously elongate mandibles. Two species are described in the genus: T. genieri, new species from Brazil Espírito Santo, and T. crenatus, new species from Colombia Caquetá.