Bro Myrddin Welsh Comprehensive School
|Motto||Heb Ddysg Heb Ddeall (Without learning there is no understanding)|
|Headteacher||Mr Dorian Williams B.A.|
|Chairman of Governors||Mr Elfed Davies|
|Local authority||Carmarthenshire County Council|
|Houses||Hengwrt, Hergest , Llwydiarth and Peniarth|
|Colours||Lilac and Black|
Ysgol Gyfun Gymraeg Bro Myrddin (English: Bro Myrddin Welsh Comprehensive School) is a Welsh-medium school in Carmarthenshire, Wales. It is situated near the village of Croesyceiliog, about 2 km south of Carmarthen. Myrddin, the Welsh name of the legendary figure Merlin, is traditionally associated with the town of Carmarthen (Caerfyrddin: Myrddin's fort), and Bro Myrddin means "Myrddin's country (or vale)".
All of the school's students speak Welsh, and most will have received a Welsh-language primary education, although many come from homes where Welsh is not the first language.
The School was founded in 1978, on the premises of the former Queen Elizabeth's Grammar School for Boys, Carmarthen. In 1996 the school was moved to its current purpose built campus at Croesyceiliog. Its first Pennaeth (Headteacher) was Mr Gareth Evans, who was succeeded upon his retirement in 1997 by Mr Eric Jones, and then by current head, Mr Dorian Williams, in 2006.
The school's motto is 'Heb Ddysg Heb Ddeall', which translates as 'Without learning there is no understanding'. The school colours are lilac and black.
The school has four houses (which are referred to using the Welsh 'Llys'): Hengwrt (house colour: green), Hergest (red), Llwydiarth (black) and Peniarth (blue). The four houses annually compete in the school's own version of the Eisteddfod, in which there is a day of singing, playing instruments, reciting and numerous other events – held on the nearest Friday to St David’s day, and a sports day held in the summer term.
2007: 82.8% of 15 year old pupils achieved 5 or more A* - C grades at GCSE or equivalent 
2007: 81.9% of 17 year old pupils achieved 2 or more A - C grades at A/AS level or equivalent 
- Core: Welsh, Maths, English and Science
- Humanities: History, Geography, and Religious Studies
- Creative subjects: Drama, Art and Design, and Music
- Technology: ICT, Resistant Materials, Catering, Health and Social Care, Textiles, Furniture *Manufacture and Graphic products
- Foreign languages: French, German, or Spanish
Other: Business Studies
Notable former pupils
- Llyr Huws Gruffydd Welsh politician
Acting, music and literature
- Euros Childs Musician, member of Gorky's Zygotic Mynci
- John Lawrence (musician) Musician, member of Gorky's Zygotic Mynci
- Richard James (musician) Musician, member of Gorky's Zygotic Mynci
- Stephen Jones (rugby player) Rugby Union player, Llanelli Scarlets & Wales national rugby union team
- Rhys Priestland Rugby Union player, Llanelli Scarlets
- Ken Owens Rugby Union player, Llanelli Scarlets
- Aled Thomas Rugby Union & Rugby Union Sevens player London Welsh, Wales national rugby union team (sevens)
- Matthew Stevens professional snooker player
- Mefin Davies Rugby Union player, Leicester Tigers & Wales national rugby union team
- Elin Llwyd Actress & Singer, notably played Katie on S4C's Pobol Y Cwm
- Tudur Phillips Presenter on S4C's Uned 5
- Gwenan Thomas - Presenter on S4C children's TV show 'Mosgito'
- Catrin Lisa Davies - Actress on S4C's 'Teulu'
- Elis James - Comedian, TV Show Panelist
- Aled Davies - Actor, played Rhys in S4C's Pobol Y Cwm