Alfonso Ugarte (July 13, 1847 – June 7, 1880) was a Peruvian civilian turned military commander during the War of the Pacific, between Peru and Bolivia against Chile.

At the beginning of the War of the Pacific, Ugarte was about to leave the country for a business trip to Europe, but instead he decided to stay in order to organize a battalion using his own money.

Ugarte was head of the Eighth Division in the defense of the city of Arica, where he participated in the two military councils held by Colonel Francisco Bolognesi, where the agreement was made to defend the bastion "until burning the last round".

He rode his horse over the Rock of Arica in order to prevent the Peruvian flag, which he was carrying, from being captured by the Chilean troops.

Ugarte is today venerated as a Peruvian national hero and his sacrifice in Arica together with Colonel Bolognesi and the rest of the garrison is remembered in Peru's Day of the Flag.