Margaret Hassan (also known as Madam Margaret) (April 18, 1945–November, 2004) was an Irish aid worker who had worked in Iraq for many years until she was abducted and murdered by unidentified kidnappers in Iraq in 2004, at the age of 59.

She was born Margaret Fitzsimmons in Dalkey, County Dublin, Ireland, to parents Peter and Mary Fitzsimmons. However, soon after the end of World War II her family moved to London, England, where she spent most of her early life and where her younger siblings were born. At the age of twenty seven, she married Tahseen Ali Hassan, a twenty-nine-year-old Iraqi studying engineering in the United Kingdom. She moved to Iraq with him in 1972, when she began work with the British Council of Baghdad, teaching English. Eventually she learned Arabic and became an Iraqi citizen, as was required of foreigners under Saddam Hussein's government.

She remained a Roman Catholic throughout her life and never converted to Islam as was widely reported after her death. A requiem Mass was held for her, after her death was confirmed, at Westminster Cathedral by Cormac Cardinal Murphy-O'Connor.