Blanche Kelso Bruce was a US Senator from Mississippi; the first black man to serve a full term in the senate, and the first person born into slavery to preside over the senate. While serving in the senate, he was an advocate for civil rights for blacks, native Americans, Chinese immigrants and former Confederates (as we remember, the radical republicans weren't too nice to that group).
After serving in the Senate, Bruce held many government appointments, including Register of the Treasury (appointed by President Garfield), recorder of deeds for DC, and a second term as Register of the Treasury. Bruce was the first African American to be represented on US currency, in the form of his signature as Register of the Treasury.
Register of the Treasury
05/21/1881 through 06/05/1885
12/03/1897 through 03/17/1898