John Jones Pettus (October 9, 1813 – January 25, 1867) was an American farmer and politician who served as the 23rd Governor of Mississippi, from 1859 to 1863. Prior to being elected in his own right to full gubernatorial terms in 1859 and 1861, he served as acting governor from January 5 to 10, 1854, following the resignation of Henry S. Foote. A member of the Democratic Party, Pettus had previously been a Mississippi state representative, a member and president of the Mississippi Senate. He strongly supported Mississippi's secession from the Union in 1861 and sought cooperation with the Confederate States Government.