Zachary is a city in East Baton Rouge Parish, Louisiana, United States. The population was 11,275 at the 2000 census.

Zachary was named for a local farmer who owned the land that became the present city of Zachary. The first post office opened in 1885, and it was incorporated as a city in 1889. The first census in 1914 reported just 419 residents. By 1980, there were 7,525 residents, in 2015 there were over 13,000 residents. Zachary was the first city in Louisiana to elect a Republican as mayor in 20th-century Louisiana.