Granville Owen Haller (1819-1897) was a US Army military officer who became a wealthy and prominent Seattle businessman. In1852, G.O. Haller was promoted to Major and was transferred from service in the Mexican-American War to the Washington Territory. During his service in the Civil War he was dismissed in 1863. In 1883, he returned to the Seattle area and began a business on Whidbey Island in Coupeville. After some time, he built the mansion known as Castlemount on First Hill (it was located on the corner of Minor and James but is no longer in existence). Haller Lake is named for his his son, Theodore Haller.