Dean Kevin O'Brien (born 15 May 1990 in Sandton) is a South African tennis player.
He played college tennis for the Georgia Tech Yellow Jackets.
O'Brien has a career high ATP singles ranking of 507 achieved on 21 April 2014.
He also has a career high ATP doubles ranking of 115 achieved on 23 May 2016.
He has won 6 ITF doubles titles.
O'Brien won his first ATP Challenger title at the 2015 Levene Gouldin & Thompson Tennis Challenger in the doubles event partnering Ruan Roelofse.
Playing for the South Africa in Davis Cup, O'Brien has a W/L record of 1–2.