Clifford "Cliff" Byrne (born 26 April 1982) is an Irish former footballer, who is currently Assistant Manager at Peterborough United. Byrne previously played for Sunderland. He took part in a UEFA 'B' coaching course in summer 2005. On 27 July 2012, it was announced that Byrne had signed for Oldham Athletic. Byrne scored his first goal for Oldham against his old club Scunthorpe United in a 2–2 draw on 1 January 2013 He rejoined former club Scunthorpe on loan in September 2013. On 17 January 2014, Cliff had his contract at Oldham Athletic cancelled by mutual agreement.