Oscar James Dunn (1826 – November 22, 1871) was one of three African Americans who served as a Republican Lieutenant Governor of Louisiana during the era of Reconstruction.
In 1868, Dunn became the first elected black lieutenant governor of a U.S. state. He ran on the ticket headed by carpetbagger Henry Clay Warmoth, formerly of Illinois. After Dunn died in office, then-state Senator P. B. S. Pinchback, another black Republican, became lieutenant governor and thereafter governor for a 34-day interim period.
On December 22, 1866, Dunn testified before a select committee appointed to investigate the New Orleans Riot of July 30, 1866. He told the committee that he was "born in New Orleans in 1826 and was about forty-one years old". His parents were James and Maria Dunn. His father, James Dunn of Petersburg, Virginia, had been emancipated in 1819 by James H. Caldwell in New Orleans. James Dunn became a free man of color and later emancipated his wife, Maria, and their two children, Oscar and Jane, in 1832. James Dunn worked as a carpenter for James H. Caldwell (founder of the St. Charles Theatre and New Orleans Gas Light Company);