Onesimos is considered one of the finest cup painters of the generation succeeding the Pioneers. We know Onesmimos' name from a signed cup in Paris made for him by Euphronios, whose own painting career was by then over. According to Boardman (Athenian Red Figure Vases, The Archaic Period, p. 133) "While Onesimos' style is readily definable from his signed vase the earlier stages of his career remain problematic, since his style develops from a fine late sixth-century group of cups related to Pioneer work (recall Euphronios the painter's cups). Beazley came to agree with earlier scholars that works assembled for a Panaitios Painter were by Onesimos, and that he emerges from a late sixth-century Proto-Panaitian Group. ...Some ten other cups made by Euphronios are painted by Onesimos or artists of his studio, so we can regard this as a single workshop."
The hoplitodromos, a footrace between nude competitors armed with greaves, helmet and shield, made its appearance in the Olympic Games in 520 B.C. (see p. 23 in Herrmann and Kondoleon, Games for the Gods, The Greek Athlete and the Olympic Spirit). Other cups by Onesimos with a hoplitodromos in the tondo are in the Sackler Museum, Harvard University (no. 22 in Hanfmann, et al., The Frederick M. Watkins Collection) and the Antikenmuseum und Sammlung Ludwig, Basel (no. 230 in Boardman, Athenian Red Figure Vases, The Archaic Period).