Margaret Copley Thaw (January 9, 1877 – January 9, 1942) was the , and a philanthropist. She was born on January 3, 1877 to William Thaw and Mary Sibbet Copley. In 1898, she married (1876–1921), the nephew of industrialist Andrew Carnegie. She died on January 9, 1942, at Kongoni Farm in what was then the British East African colony of Kenya. The farm and a life interest in her $2,000,000 estate was left to her husband.