Mary O'Connell

Mary O'Connell may refer to:
 * Mary O'Connell (nurse) (1814–1897), Irish-born American Roman Catholic religious sister and nurse during the American Civil War
 * Mary O'Connell (1778–1836), Irish wife of Daniel O'Connell
 * Mary J. O'Connell, Irish evolutionary genomicist
 * Mary Ellen O'Connell, American professor of law