1920s|Prince of Wales - George (later George V)
Princess of Wales - Mary
Archdruid of the National Eisteddfod of Wales - Hwfa Môn
January - Opening of Llanelli North Dock.
5 January - Opening of Tanat Valley Light Railway between Lynclys and Llangynog.
February - Beginning of the 1904-1905 Welsh Revival.
4 May - Frederick Henry Royce meets Charles Stewart Rolls to discuss the Rolls-Royce agreement.
21 July - Edward VII and Queen Alexandra open the Elan Valley Reservoirs.
3 August - The first Royal Welsh Show is held in Aberystwyth.
28–29 September - A conference at Blaenannerch reinforces the strength of the religious revival.
October - Evan Roberts begins preaching.
31 October - Rhondda Tramways Company begins operation.
3 October - Five people are killed in a railway accident near Loughor.
November - Joseph Jenkins, instigator of the religious revival, is guest preacher at meetings in Bethany, Ammanford, and "converts" incumbent minister Nantlais Williams.
30 November - Philip Burton, theatre director and radio producer
Second Meeting of the Celtic Association is held at Caernarfon.
Orthopaedic surgeon Robert Jones becomes Honorary Surgeon to the Baschurch Home in Shropshire, which he will develop into the world's first specialized orthopaedic hospital.
Millicent McKenzie is appointed a professor at the University College of South Wales and Monmouthshire in Cardiff, the first woman appointed to a chair at a British university-level institution.
Thomas Marchant Williams is knighted in recognition of his role in founding the National Eisteddfod Society.
In local authority elections, the Liberal Party win control of all county councils in Wales.
February - Gwen John arrives in Paris, in the company of Dorelia McNeill.
National Eisteddfod of Wales - held in Rhyl
Chair - J. Machreth Rees
Crown - Richard Machno Humphreys
J. Romilly Allen - Celtic Art in Pagan and Christian Times
Joseph Bradney - A History of Monmouthshire: From the coming of the Normans into Wales down to the present time, vol. 1
Owen Dafydd (died c. 1814) - Cynhyrchion Barddonol yr Hen Felinydd Owen Dafydd Cwmaman
Eluned Morgan - Dringo'r Andes
Silyn Roberts - Trystan ac Esyllt a Chaniadau Eraill
Sir Henry Walford Davies - Everyman (oratorio)
Rugby league - In the first international league match, played between England and Other nationalities, ex-Wales rugby international Jack Rhapps becomes the World's first dual-code rugby international.
Rugby union - Percy Bush scores 104 points for the British team on their tour of Australia and New Zealand.
March - Daniel Granville West, Baron Granville-West, politician (died 1984)
6 March - Hugh Williams, actor and dramatist (died 1969)
12 April - David Jenkins, Wales national rugby footballer (died 1951)
18 May - Eynon Evans, actor and screenwriter
7 June - Tom Lewis, Wales international rugby player (died 1994)
8 June - Angus McBean, photographer (died 1990)
26 June - Prof Seaborne Davies, law teacher and three times President of the National Eisteddfod (died 1984)
27 June - Emrys Davies, cricketer (died 1975)
29 June - Lynn Ungoed-Thomas, politician (died 1972)
28 July - Ned Jenkins, Wales international rugby player (died 1990)
31 July - Harold Davies, Baron Davies of Leek, politician (died 1985)
4 August – Sir Thomas Parry, academic (died 1985)
8 August - Dai Parker, Wales and British Lion rugby player (died 1965)
22 August - Tommy Rees, Wales dual-code rugby player (died 1968)
12 September – Euros Bowen, poet (died 1988)
12 September – Donald Holroyde Hey, chemist (died 1987)
24 September - George Andrews, Wales dual-code rugby player (died 1989)
27 September - John Gwilym Jones, dramatist (died 1988)
30 September - Waldo Williams, poet (died 1971)
10 October (in Somerset) – Leslie Morris, politician in Canada (died 1964)
15 October - Sir Julian Hodge, banker (died 2004)
3 November - Caradog Prichard, poet and novelist (died 1980)
Richard Vaughan, novelist (died 1983)
21 April - William Williams, businessman and politician, 64
10 May - Sir Henry Morton Stanley, journalist and explorer, 63
26 June - William Ormsby-Gore, 2nd Baron Harlech, 85
12 July – Samuel M. Jones, mayor of Toledo, Ohio, USA, 57
17 July - Isaac Roberts, astronomer, 75
25 July - James Valentine, English rugby international, 37 (struck by lightning while on holiday in Barmouth)
September - Benjamin Davies, Welsh-descended Canadian politician, 91
21 November - Jimmy Michael, cyclist, 27 (alcohol-related)
24 November – Lewis Jones, one of the founders of the Welsh settlement in Patagonia, 68
24 November – Evan Lewis, Dean of Bangor, 86
29 December - Edward Treharne, Wales international rugby player, 42 (heart attack)
James Lewis Thomas, architect
1904 in Wales Wikipedia
This article is about the particular significance of the year 1904 to Wales and its people.