Mary Catherine Judd (March 12, 1852 – October 1937) was an American educator, author of children's literature, and active worker for world peace.

Born in New York state, she lived for many years in Minnesota, and in later life, in southern California.

She descended on her father's side from Deacon Thomas Judd, an English colonist, 1633, Cambridge, Massachusetts, and official in the Colonial assembly of Connecticut in 1639.

In July 1901, Rand & McNally brought out an enlarged and profusely illustrated edition of Judd's Class Myths.

[7] When Jane Addams was appointing delegates to the Hague Peace Conference of April 1915, she named Judd, who was, however, unable to attend.

[7] Judd was appointed by Governor Winfield Scott Hammond a delegate to the International Conference of Women Workers to Promote Permanent Peace held at the Panama–Pacific International Exposition in July 1915;[1] it was Judd's intention to urge that this conference take action looking to have a peace emblem placed on postage stamps.