- Queen Elizabeth I The fifth and last monarch of the Tudor dynasty.
- Queen Mary I The fourth crowned monarch of the Tudor dynasty, remembered for restoring England to Roman Catholicism.
- Rebecca Riots History blog on the rural riots the took place between 1839 and 1843 in south and mid Wales.
- Red dragon of Cadwallader By the seventh century, the red dragon was known as the red dragon of Cadwallader.
- Referendum for devolution (1979) Held on 1 March 1979 (St David's Day) in Wales the outcome was a resounding four-to-one vote against devolution.
- Reformation (The) A movement began to reform the Catholic Church.
- Religion 91Èȱ¬ Wales site on the history of religion in Wales.
- Reynal de Grey Anti-Welsh Norman landowner of Dyffryn Clwyd, captured by Owain Glyndwr in 1401.
- Rhys ap Gruffudd Ruler of the kingdom of Deheubarth in South Wales.
- Rhys ap Tewdwr Prince of Deheubarth in West Wales.
- Saunders Lewis (John Saunders Lewis) was a prominent Welsh nationalist and founder of the Welsh National Party (later known as Plaid Cymru).
- St. David Native Welshman who became the patron saint of Wales.
- Sir Edmund Mortimer Captured by Owain Glyndwr and subsequently renounced his allegiance to King Henry IV.
- Sir John Price Responsible for the first book to be printed in Welsh, Yn y Lhyvr Hwnn.
- Slate mining The seams of slate around Dinorwig, Llanberis, Bethesda and Blaenau Ffestiniog are some of the highest quality in the world.
- Sons of Glyndwr In the early 1980s campaigners torched holiday homes as a protest against rising house prices. Responsibility was claimed by Meibion Glyndwr, the Sons of Glyndwr.
- South Wales Miners' Federation (SWMF) Formed after the South Wales Miners' Strike of 1898.
- St David A church official in the sixth century, St David later became the patron saint of Wales.
- Statute of Labourers Statute of Labourers of 1563 which assumed that those without property were inherently unfree.
- Suffragettes The name 'suffragettes' comes from the word 'suffrage' - the right to vote. In the early 20th century, there were over 50 organisations in Britain campaigning for votes for women.
- Temperance Movements set up in the late 19th to promote complete abstinence from alcohol.
- The Thirty Nine Articles Established in 1563, these articles form the basic summary of belief of the Church of England.
- Thomas Capper Burnt at the stake in Cardiff for heresy. A radical Protestant, he was the first religious martyr in Wales since Roman times.
- Tonypandy Riots History blog on the riots took place on the evenings of 7 and 8 November 1910, and involved violent clashes between striking miners and members of the Glamorganshire Constabulary - backed up by both the Bristol and the Metropolitan police.
- Tostig Godwinson An Anglo-Saxon earl of Northumbria and brother of King Harold II of England, the last crowned Anglo-Saxon King of England.
- Treachery of the Blue Books The name given in Wales to the Reports of the commissioners of enquiry into the state of education in Wales published in 1847.
- Tudors The Tudor dynasty or House of Tudor was an English royal dynasty that lasted 118 years, from 1485 to 1603.
- Tudur Fychan Lord of Pemmynydd and married to Margaret ferch Thomas of the Gwynedd royal family.
- Tynged Yr Iaith Tynged Yr Iaith (The Fate of the Language). The name of the 1962 91Èȱ¬ radio lecture given by Saunders Lewis.
