Rotha Mary Clay (17 September 1878 – 1 March 1961) was a British self-taught historian and social worker.

Her parents were the diarist Jessy (born Allan) and the amateur painter John Harden Clay.

[2] At the end of 1895 she started the only known formal education when she began a year of study at Queen's College, London.

By the twentieth century she was exploiting Bristol University's Library to study the history of medieval hospitals in England.

She bought Ilex Cottage in the High Street of Shirehampton where she lived with Rosa Higgs.