Pacífica Fernández Oreamuno (August 23, 1828 – March 31, 1885) was the inaugural First Lady of Costa Rica and wife of President José María Castro Madriz.

[1] She was born in San José, Costa Rica on August 23, 1828 to her parents former Head of State Manuel Fernández Chacón and Dolores Oreamuno Muñoz de la Trinidad, and was sister of President Próspero Fernández Oreamuno.

[2] She married José María Castro Madriz on June 29, 1843, who later became Head of State (1847–1848) and President of the Republic of Costa Rica (1848–1849 and 1866–1868).

She still holds the title as the youngest First Lady or spouse of a Costa Rican head of state, as she was only 18 when her husband first gained power.

[5] Fernández died in San José, Costa Rica on March 31, 1885.