John Gregg was an American politician who served as a deputy from Texas to the Provisional Congress of the Confederate States from 1861 to 1862. He served as a brigade commander officer of the Confederate States Army and was killed in action during the Siege of Petersburg.

The Provisional Congress of the Confederate States, also known as the Provisional Congress of the Confederate States of America, was a unicameral congress of deputies and delegates called together from the Southern States which became the governing body of the Provisional Government of the Confederate States from February 4, 1861, to February 17, 1862. It sat in Montgomery, Alabama, until May 21, 1861, when it adjourned to meet in Richmond, Virginia, on July 20, 1861. In both cities, it met in the existing state capitols which it shared with the respective secessionist state legislatures. It added new members as other states seceded from the Union and directed the election on November 6, 1861, at which a permanent government was elected.