Casilda Iturrizar (1818 – 22 February 1900), also known as the Epalza widow, was a Spanish philanthropist and businessperson from Bilbao in the Basque Country.

She also contributed to many Catholic organizations such as the Claretians of the San Francisco neighborhood, the Servants of Jesus de La Naja and the Augustinians of Portugalete.

[4] She also joined the Catholic Foundation of Schools and Workers' Board of Trustees in 1891 to advance its goal of offering "completely free teaching, moralization, recreation and protection to the working class.

][5] She had no children or direct descendants so 7.5 million pesetas of her fortune (which did not represent the full amount[1]), was bequeathed to many social organizations after her death, including the Casa de Misericordia and the Civil Hospital.

Iturrizar is also memorialized on the Bilbao street where she lived, Viuda de Epalza, with a plaque that says (in Spanish):"Year MCDCCCC.