Terence O'Brien or Terrence O'Brien may refer to:

• Terence O'Brien (actor) (1887–1970), Irish-born British actor
• Terence O'Brien (British diplomat) (1921–2006), British Ambassador to Nepal, 1970–1974, Burma, 1974–1978, and Indonesia, 1978–1981
• Sir Terence O'Brien (colonial governor) (1830–1904), British Governor of Newfoundland, 1889–1895
• Terence O'Brien (New Zealand diplomat) (1936–2022), New Zealand Ambassador to the United Nations, 1980–1983, 1990–1993, and the European Community, 1983–1986
• Terence O'Brien (rower) (1906–1982), English Olympic rower
• Terence O'Brien (bishop) (1600–1651), Irish Roman Catholic bishop of Emly
• Terrence O'Brien (director), American founder and director of the Hudson Valley Shakespeare Festival
• Terrence L. O'Brien (born 1943), United States federal judge