Horace J. Jackson (August 1845 – January 7, 1915) was an American drayman, dockworker and politician who served in the California State Assembly from 1881 to 1883. A founding member of the Workingmen's Party of California, he was elected in 1880 on a Workingmen's-Democratic Fusion ticket. He was later active in Democratic and Union Labor Party politics.
Jackson served in the Union Army under General George McClellan during the Civil War. He was a member of the Riggers' and Stevedores' Union and spoke in favor of the Union Labor Party shortly after its foundation. As the San Francisco Examiner wrote: