Sir Brendan Paul Barber is a British trade union official. He served as chair of the Advisory, Conciliation and Arbitration Service (ACAS) Council until 2020. He is a former general secretary of the United Kingdom's Trades Union Congress (TUC); a post he held from June 2003 until his retirement at the end of 2012. He was appointed Acas Chair in 2014, replacing Ed Sweeney, who had been in the post since 2007. He also serves on the board of the Banking Standards Board (2015–), the Board of Transport for London (2013–), the board of Britain Stronger in Europe (2015–), the Council of City University, London and the board of Mountview Academy of Theatre Arts (2014–).

The General Secretary of the TUC is the chief permanent officer of the Trades Union Congress, and a major figurehead in the trade union movement in the United Kingdom.