Henry O'Brien may refer to:
Henry O'Brien, Lord Ibrackan (c. 1642–1678), Irish nobleman and politician Henry O'Brien, 5th Earl of Thomond (1588–1639), Irish peer Henry O'Brien, 7th Earl of Thomond (c. 1620–1691), Irish peer Henry O'Brien, 8th Earl of Thomond (1688–1741), Irish peer and Member of Parliament Henry O'Brien (Australian politician) (1793–1866), Irish-born New South Wales politician Henry O'Brien (classicist) (1808–1835), Irish classicist and author Henry O'Brien (colonel) (died 1863), colonel of the 11th New York Volunteer Infantry Regiment killed during the New York draft riots Henry O'Brien (cyclist) (1910–1973), American cyclist Henry D. O'Brien (1842–-1902), Medal of Honor recipient from the American Civil War Henry Joseph O'Brien (1896–1976), American prelate of the Roman Catholic Church Henry L. O'Brien (c. 1869–1935), American politician from New York Henry X. O'Brien (c. 1903–1990), American lawyer and judge