re: Cory "Retardacus" Booker introduces Senate bill on slavery reparations

You're talking about William " April" Ellison Jr who was the largest black slave owner out of 171 black slave owners in South Carolina.
The largest slave owner in SC was also the largest slave owner in America and he was a white guy.

Joshua John Ward, of Georgetown County, South Carolina, was the largest American slaveholder, dubbed "the king of the rice planters". In 1850 he held 1,092 slaves; Ward was the largest slaveholder in the United States during his lifetime. In 1860 his heirs (his estate) held 1,130 or 1,131 slaves.

Note: April Ellison Jr was the largest slave owner in the area of Columbia and Sumter.