Oh Jung-se (born February 26, 1977) is a South Korean actor. Oh began his career in theater, and has since appeared in many onscreen supporting roles over the years, notably in Petty Romance (2010), Couples (2011), As One (2012), A Millionaire On the Run (2012), and Running Man (2013). But his performance in the 2013 romantic comedy How to Use Guys with Secret Tips earned him special attention from critics and viewers. This led to Oh being cast in his first leading role in the 2013 film The Hero.