Margaret Hessen und bei Rhein

Margaret, Princess of Hesse and by Rhine (born Margaret Campbell Geddes, 18 March 1913 – 26 January 1997) was the wife of Louis, Prince of Hesse and by Rhine, the last prince of the House of Hesse-Darmstadt. Born in Ireland, she became a noted art patron in her adopted homeland of Germany.

Geddes was born in Dublin, Ireland to Auckland Campbell Geddes, a British academic later made Baron Geddes, and his wife, Isabella Gamble Ross. Her father was a member of David Lloyd George's coalition government during World War I, and later served as Ambassador to the United States.

At the 1936 Winter Olympics in Garmisch-Partenkirchen, Germany, Margaret met Prince Louis of Hesse and by Rhine, the second son of Ernest Louis, last Grand Duke of Hesse. They became engaged the next year. The wedding date was set for 18 November 1937. Planning continued despite the groom's father's death on 9 October.

On 16 November 1937, while travelling to London for the wedding, Prince Louis' mother, Grand Duchess Eleonore, brother, Hereditary Grand Duke Georg Donatus, sister-in-law, Hereditary Grand Duchess Cecilie, nephews, Prince Louis and Prince Alexander, and Georg Donatus' and Cecilie's newborn child, were killed in the Sabena Junkers Ju 52 Ostend crash over Ostend, Belgium. Louis succeeded his brother as titular Grand Duke of Hesse and by Rhine.

The day after the crash, on 17 November 1937, Margaret and Louis were married at St Peter's Church, Eaton Square. The newlyweds were dressed in mourning and swiftly returned to Darmstadt for the funerals. The couple had no children but adopted Louis' niece, Princess Johanna, after her parents perished in the crash. She died of meningitis in 1939 at the age of 2.

After her marriage, Margaret devoted herself to the arts and museums in Darmstadt. She is credited with helping the British royal family reestablish connections with their German relations after World War II. Louis died in 1968; with his death, the House of Hesse-Darmstadt became extinct.

Margaret's 80th birthday celebrations in 1993 were attended by the Prince of Wales.

She died on 26 January 1997. Her funeral, held on 31 January 1997 at the Stadtkirche Darmstadt, was attended by Queen Anne-Marie of Greece, the Duke of Edinburgh, the Prince of Wales and Princess George William of Hanover.

• 18 March 1913 – 17 November 1937: Miss Margaret Campbell Geddes
• 17 November 1937 – 26 January 1997: Her Royal Highness The Princess of Hesse and by Rhine