| Llangammarch | |
| Official Name: | Ecclesiastical Parish of Llangammarch |
| Type: | Parish |
| Coordinates: | 52.1137°N -3.5582°W |
| Subdivision Type1: | Country |
| Subdivision Name1: | Wales |
| Subdivision Type2: | Local government county |
| Subdivision Name2: | Powys |
| Subdivision Type3: | Historic county |
| Subdivision Name3: | Brecknockshire |
| Subdivision Type4: | Diocese |
| Subdivision Name4: | Swansea and Brecon |
| Blank Name Sec1: | Dedication |
| Blank Info Sec1: | St Cammarch |
| Blank1 Name Sec1: | OS grid reference |
| Blank2 Name Sec1: | Deposited registers |
| Blank2 Info Sec1: | 1763-1971 |
Llangammarch was a rural ecclesiastical parish in Powys, mid-Wales, through which flow the rivers Irfon and Cammarch. The main centre of population is the spa village of Llangammarch Wells. It is in the historic county of Brecknockshire (Breconshire).
John Penry, Wales's most famous Protestant martyr, was born at Cefn Brith, a farm near Llangammarch, which is traditionally recognised as his birthplace.
Llangammarch Community embraces Cefn Gorwydd and Tirabad. Llangammarch has an active history society and many activities in the Alexandra Hall.