Captain August Thayer Iaccaci, Sr. (6 June 1893 – 30 April 1980) was a US-born World War I flying ace who, together with his gunners, was credited with 17 aerial victories.

He was born to Augusto Florian Iaccaci (1857–1930) and Mabel Thayer on 6 June 1893 in Hingham, Massachusetts.

He worked for H. K. McCann Co. until he went to Canada and joined the Royal Flying Corps along with his older brother Paul in 1917.

With the exception of one reconnaissance two-seater, August Iaccaci triumphed over German fighter planes and pilots.

His father died on 22 July 1930 at Châteauneuf-Grasse in France and named his son[clarification needed] as his heir.