Hypomyces completus is a parasitic ascomycete in the order Hypocreales.

The fungus grows on boletes, typically Suillus spraguei in North America, although the type collection was found on growing on Boletinus oxydabilis in Siberia.

[2] The species was described as new to science in 1971 by G. R. W. Arnold, who placed it in Peckiella, a genus segregated from Hypomyces by Pier Andrea Saccardo to contain species having unicellular ascospores.

In their 1989 review, Rogerson and Samuels did not accept this genus as valid, stating "variations in these features occur, occasionally in a single perithecium", and they reclassified the fungus in Hypomyces.

The anamorph species associated with H. completus is Sepedonium brunneum, first described by Charles Horton Peck in 1887.