|Motto||Gorau gwaith gwasanaeth ('[Your] best work is to serve')|
|Head||Mrs. Rhian Phillips|
|Chair||Mr Ceri Morgan|
|Location||Llanharry (nr Pontyclun)
Rhondda Cynon Taf
|Local authority||Rhondda Cynon Taf|
|Colours||Black and Red|
Llanhari is one of the older Welsh medium secondary schools in the area, having opened in 1974. It followed Ysgol Gyfun Rhydfelen in the vanguard of such schools in South Wales. Over time, it became apparent that Llanhari would not be able to cope with the pupil numbers, as it was oversubscribed, and in 1978, Ysgol Gyfun Gymraeg Glantaf opened in Cardiff in order to take the South Glamorgan pupils and relieve Llanhari. On 6 June 2011, it was publicly announced that from 2012 the school would incorporate a primary unit and become a 3-18 school. On 3 September 2012, the Primary Unit was opened and the school was formally designated a 3-18 school with the new name of Ysgol Llanhari. Mrs Catherine Webb is Assistant Head with responsibility for this unit.
Ysgol Y Ferch o'r Sger, Ysgol Bro Ogwr, Ysgol Gynradd (Ffrwd Gymraeg) Dolau, Ysgol Cynwyd Sant, Ysgol Gymraeg Tonyrefail, Ysgol Gymraeg Cwm Garw and Ysgol Gynradd Gymraeg Gymunedol Llantrisant were, until the opening of Ysgol Gyfun Llangynwyd in 2008, the primary schools that fed Ysgol Gyfun Llanhari. However, since the advent of Ysgol Gyfun Gymraeg Llangynwyd, Llantrisant, Tonyrefail and Dolau are now the only main feeder schools to Ysgol Llanhari.
To date, Ysgol Llanhari has been led by five heads. Mrs Rhian Phillips is the current headteacher at the school. She succeeded Mr Meirion Stephens, who served as head of Llanhari from January 2008. He was preceded by Miss T Anne Morris, who took over in 2003. Prior to this, Mr Peter Griffiths, father of Ioan Gruffudd, star of such films as Fantastic Four and Wilde served as head from 1989. The original head when the school opened in 1974 was Mr Merfyn Griffiths.
Head of Years
Miss Angharad Morgan is the current Head of Year for Year 7 and 8. Miss Leana Stansfield is the current Head of year for Years 9 and 10 and Mr Stephen Wilshaw is Head of Year for Years 11, 12 and 13.
Examination results have consistently improved since 2008. In 2012, 75% of pupils attained grades A*-C in all A-Level subjects sat, and 97% were awarded grades A-E in all subjects. At GCSE, 74.2% of all grades awarded were A*-C and 74.6% of students attained the 5 A*-C benchmark.
Notable former/current pupils
- Garnon Davies, Known for his role as Elliot Bevan in Channel 4's Hollyoaks
- Bethan Ellis Owen, who is best known for her role as Ffion Llewelyn in Pobol y Cwm.
- Shelley Rees, who played Stacey Jones in Pobol y Cwm
- Gareth Wyatt the Welsh international Rugby player
- Scott Gibbs the Welsh international Rugby player
- Guto Harri is a former BBC Chief Political Correspondent. In May 2008 he was appointed as Communications Director for the Mayor of London Boris Johnson's administration at London City Hall.
- Betsan Powys is a Welsh journalist, currently the political editor for BBC Wales
- Rhys Williams, is a Welsh professional athlete, specialising in the 400 m hurdles
- Aled Siôn Davies, Paralympian
- Ysgol Llanhari website. Accessed 26 December 2015.
- Carrie Evans, 'Ysgol Llanhari celebrates 40 years of Welsh language education', Wales Online, 30 October 2014. Accessed 26 December 2015.
- "Inspection under Section 10 of the School Inspections Act 1996" (PDF). Estyn. Retrieved 26 April 2008.
- Merfyn Griffiths, 'Growth in Secondary Education in Mid Glamorgan', in Iolo Wyn Williams (ed.), Our Children's Language: The Welsh-medium Schools of Wales 1939–2003 (Talybont, 2003), p. 115; retrieved 23 September 2013.
- My Local School: Ysgol Llanhari; retrieved 23 September 2013.
- "Pobol Y Cwm Characters". Archived from the original on 13 March 2008. Retrieved 2 August 2008.