Trwyn Du/Penmon
| Location | SH 64148 81499 / 53.3130, -4.0406 / verb.cringes.slows |
| Established / Rebuilt / Automated / Closed | 1838 / — / 1922 / — |
| Architect or Builder | James Walker |
| Height of tower (m) / above sea level (m) / Range (NM) | 22 / 19 / 12 |
| Character | Fl 5s |
| Optic | LED, 2021 (previously 1st order fixed catadioptric) |
| Owner | Trinity House |
The building of this lighthouse, which marks the entrance to the Menai Strait, was prompted by the sinking nearby of the Rothsay Castle paddle steamer in 1831, with the loss of 130 lives. One of the defining features of the tower is the stepped base, which was designed to dissipate the power of waves. It was one of the first Trinity House lighthouses to be automated.