Francisco Adolfo de Varnhagen, Viscount of Porto Seguro (February 17, 1816 – June 26, 1878), was a Brazilian diplomat and historian.

He was the son of Maria Flávia de Sá Magalhães and Friedrich Ludwig Wilhelm Varnhagen, a German-born military engineer, who was in service to the Portuguese crown and in Brazil to inspect iron foundries.

He was admitted at the Sciences Academy of Lisbon and graduated in military engineering at the Academia Real de Fortificação, Artilharia e Desenho.

[5] He later served in Paraguay, where he found the current regime of Carlos Antonio López odious, but he gathered further materials for his history of Brazil, particularly on the Tupí Indians.

[6] He also served in Venezuela, the Republic of New Granada (modern Colombia), Ecuador, Chile (where he met his wife, an aristocratic Chilean lady Doña Carmen Ovalle y Vicuña, marrying her in 1864), Peru and the Netherlands.

"[8] In general, Varnhagen was pro-monarchy, since it gave Brazil a strong central government and took the part of Portuguese colonists in debates about the colonial era.