Oliver Albert O'Brien (1839 – October 1, 1894) was a Union Navy sailor in the American Civil War and a recipient of the U.S. military's highest decoration, the Medal of Honor, for his actions during the capture of a blockade runner. O'Brien's official Medal of Honor citation reads: O'Brien was promoted to acting master's mate before leaving the Navy. He died on October 1, 1894, at age 54 or 55 and was buried in Oak Hill Cemetery in Gloucester, Massachusetts.