Bagby (formerly Ridley's Ferry and Benton Mills) was an unincorporated community in Mariposa County, California. It was located on the north bank of the Merced River 9.5 miles (15 km) northeast of Hornitos, at an elevation of 830 feet (253 m). Lake McClure covers the original town site.

A ferry across the Merced River, operated by Thomas E. Ridley, operated at the future site of Bagby during the 1850s. This was later followed by a stamp mill at the site, established by John C. Fremont, who renamed the site Benton Mills. The name Bagby was chosen in 1897 when the post office was established, to avoid conflict with another town known as Benton Mills in Mono County.

A post office operated at Bagby from 1897 to 1951. The Bagby family operated a hotel and store along the Yosemite Valley Railroad at the site, where a power plant supplied electricity to the surrounding area. The power plant was destroyed by fire in 1922, and the townsite was destroyed when Exchequer Dam was completed in the 1960s. Some railroad-related structures from Bagby were relocated to El Portal when the town was inundated. Ruins of the townsite can still be seen when lake levels are low.