Sitiveni O. "Steve" Mafi (born 9 December 1989, Fairfield, New South Wales) is an Australian-born rugby player of Tongan heritage who plays flanker or lock for the Western Force and Tonga, having previously played for the Leicester Tigers and New South Wales Waratahs. He is the grandson of former Tonga captain Sione Mafi PahuluMafi attended Westfields Sports High School and played his Junior rugby at Parramatta Two Blues in Sydneys west. In 2007 he played for the Australian Schoolboys.