Ana de Castro Osório (18 June 1872 – 23 March 1935) was a Portuguese feminist, active in the field of children's literature and political Republicanism.

[1] In 1889, Osório married republican poet Paulino de Oliveira, with whom she had two children.

[1] In 1905, she wrote the feminist manifesto Às Mulheres Portuguesas (To Portuguese Women).

[1] Together with Adelaide Cabete and Fausta Pinto de Gama, they founded the Liga Republicana das Mulheres Portuguesas (Portuguese Women's Republican League) in 1908.

[3] The group called for the overthrow of the monarchy and contributed to the proclamation of the Portuguese Republic in 1910.