Charles Maclay (1822 or 1823 – July 19, 1890) was a California State Senator and the funder of the city of San Fernando, California in the San Fernando Valley.
Charles Maclay's heritage was from Ireland and Scotland. He was the brother of Robert Samuel Maclay, a pioneer missionary to China; and the uncle of Robert Maclay Widney, a founder of the University of Southern California, and of Joseph Widney, the second president of the University of Southern California. Maclay was a Methodist minister.
Charles Maclay became a California State Assemblyman in the 7th District from Santa Clara County (1871-1872) and later a California State Senator (1864-1872).
In 1874, Charles Maclay bought 56,000 acres (227 km2) of the Rancho Ex-Mission San Fernando land grant including the northern half of the San Fernando Valley north of the city of Los Angeles. In 1882, cousins George K. Porter and Benjamin F. Porter, owner of future Porter Ranch, each received one-third of the total land.
In 1885, Maclay founded the Maclay School of Theology, a Methodist seminary in his newly founded town of San Fernando, California. After his death it became an affiliate and moved to the campus of the University of Southern California before becoming the Claremont School of Theology in 1957.