John Belton O'Neall (1793–1863) was an American judge who served on the precursor to the South Carolina Supreme Court.

Admitted to the bar in South Carolina in May 1814, he began his legal practice, and soon his political career.

[2] In 1848 O'Neall (who was reported by a personal acquaintance to have owned "about 150" slaves and to have been "a most humane master")[3] wrote a digest of the negro law of South Carolina, which he read to the State Agricultural Society.

The Society directed him to submit the document to the governor, with a request that he would lay it before the legislature, at its approaching session in November 1848.

[4] His book was extremely controversial due to what was perceived by many slaveholding South Carolinians of the time to be its abolitionist-influenced advocacy of sharply reducing the number of crimes for which slaves could be put to death under South Carolina laws.