- Aberdare fire engine Slideshow of the restoration of a Merryweather fire engine that was one of the first emergency vehicles to attend the Aberfan disaster on Friday 21 October, 1966.
- Aberfan disaster On 21 October 1966 waste from the Merthyr Vale colliery slid down the mountainside, killing 144 people, of whom 116 were children.
- Act of Uniformity An Act passed by Edward VI in 1549 that required all acts of public worship to be conducted in English instead of Latin.
- 1536 Act of Union Passed by Henry VIII's government to intensify the sovereignty of the crown throughout his kingdom: the act decreed the law of England was to be the only law of Wales, and English was to be the only language of the courts of Wales.
- 1536 Act of Union Video archive: 'The Story of Welsh'. How the Act of Union ordered by Henry VIII in 1536 signalled problems for the Welsh language.
- 1543 Act of Union Seven years after its predecessor, the act established the Court of Great Session, a distinct Welsh system of courts based upon four three-county circuits.
- The afanc Emigration of Welsh people to America who embarked to find an enhanced way of life in the New World.
- America-Wales migration Emigration of Welsh people to America who embarked to find an enhanced way of life in the New World.
- Aneirin Author of Y Gododdin.
- Aneurin Bevan Labour radical, a socialist sympathiser who established the National Health Service.
- Angelystor A recording Angel who on Hallowe'en and 31 July is said to appear in the medieval church of Llangernyw in Conwy. And announces, in Welsh, the names of those parish members who will die shortly after.
- Anne Boleyn The second wife of King Henry VIII and the mother of Queen Elizabeth I.
- Arthur Scargill Leader of the National Union of Mineworkers (NUM) from 1981 to 2000.
- Australia-Wales migration The first Welsh emigrants to Australia were convicts, though mining brought significant numbers of settlers.
- Banner of Owain Glyndwr The lion on red and gold was carried into battle during Owain Glyndwr's rebellion against the English.
- Benedictines Autonomous communities of monks who suffered directly under the rule of Henry VIII.
- Bible in Wales Following legislation introduced by Elizabeth I, all churches in Wales were required to have Welsh translations of the Book of Common Prayer and the Bible alongside the English versions by 1567.
- Bilingualism The 1980s saw a growing cross-party consensus on the Welsh language.
- Bishop William Morgan Translated the Bible into Welsh.
- Black History Month A celebration of black history and the contributions of black people worldwide.
- Cadwallon ap Gruffydd Key figure in Welsh resistance to Norman rule and remembered as King of all Wales.
- Caratacus (Caradog) British chieftain who led the British resistance to the Roman conquest. He may correspond with the legendary Welsh character Caradoc.
- Catherine of Aragon Spanish princess, the first wife of Henry VIII and mother of Queen Mary.
- Catholicism Elements within Welsh society remained faithful to Roman Catholicism.
- Celts The story of Wales begins with a group of tribes collectively referred to as the Celts.
- Celts (Children's site) Games, stories and activities about the Iron Age Celts for 7-11 year olds.
- Lady Charlotte Guest Best known for her pioneering translation of the Mabinogion.
- Chartism A movement for democratic rights, started in London in 1838 with the publication of the 'People's Charter'.
- Cistercians Roman Catholic religious order of enclosed monks.
- Civil disobedience Since 1925, groups have used civil disobedience to campaign for the Welsh language.
- Christmas traditions History blog on Welsh festive traditions.
- Cleddau Bridge History blog on the Cleddau Bridge in south Pembrokeshire that collapsed during the construction process on 2 June 1970.
- Cowboys History blog on the Welsh settlers who lived in the American West.
- The Dark Ages The term Dark Ages commonly refers to the European Early Middle Ages, from around 475 to the turn of the second millennium AD.
- David Lloyd George The first, and so far only, Welsh prime minister.
- Dr John Davies Welsh historian, and a television and radio broadcaster. His publications include Hanes Cymru, A History of Wales and Broadcasting and the Â鶹Éç in Wales.
- Y Ddraig Goch The red dragon on a green and white background has been the official flag for Wales since 1959.
- Devolution Self government, or devolution, had first been raised by the Liberal party during the late 19th century.
- DJ Williams Leading member of Plaid Cymru.
- Dolaucothi mine Gold mine in Llanwrda, Carmarthenshire.
- Druids The 18th-century revival of the ancient druidic order of the Gorsedd of the Bards.
- Edmund Mortimer The Earl of March, captured by Owain Glyndwr in his victory at Bryn Glas (Pilleth) in June 1402.
- Edmund Tudor (Earl of Richmond) Half brother of Henry VI, and father of Henry VII, he was charged with securing Wales for the house of Lancaster in the mid-1450s.
- Ednyfed Fychan Welsh warrior who became seneschal to the Kingdom of Gwynedd in northern Wales.
- Edward IV England's first Yorkist King
- Edward VI A zealous Protestant who occupied the throne from 1547 to 1553.
- Edward Williams Responsible for the establishment of the Gorsedd of the Bards.
- Ellis Humphrey Evans (Hedd Wyn) Merionethshire shepherd-poet of World War I who was posthumously awarded the bardic chair at the National Eisteddfod, Birkenhead, in 1917.
- Emigration Generations of Welsh people have left the country in search of a better life and freedom from religious persecution.
- Evan Morgan History blog on the unusual life of Evan Morgan, the last Viscount Tredegar.
