| Black Mountain South Top | |
| Elevation M: | 637 |
| Prominence M: | 15 |
| Parent Peak: | Black Mountain |
| Listing: | Nuttall |
| Location: | Herefordshire, England / Powys, Wales |
| Range: | Black Mountains |
| Grid Ref Uk: | SO255350 |
| Topo: | OS Landranger 161 |
| Easiest Route: | The Cat's back |
Black Mountain South Top is a top of Black Mountain in the Black Mountains range that spreads across parts of Powys and Monmouthshire in southeast Wales. It is a top which falls exactly on the Welsh-English border, straddling Powys and Herefordshire. The Offa's Dyke Path passes over the summit.
The top is an undistinguished heathery bump on Hatterall Ridge. The summit is marked by a small pile of stones.[1]