1955 in Wales
- Prince of Wales – vacant
- Princess of Wales – vacant
- Archbishop of Wales – John Morgan, Bishop of Llandaff
- Archdruid of the National Eisteddfod of Wales – Dyfnallt
- 18 April–28 May – Charles Evans leads the mountaineering expedition that conquers Kanchenjunga.
- 20 April – Future mother of Kylie and Dannii Minogue, Carol Jones, emigrates with her family from Maesteg to Australia.
- 31 October – The A48 road bridges over the River Neath at Briton Ferry (six years in the building) are officially opened by the Minister of Transport.
- 3 December – The Farmers Union of Wales breaks away from the National Farmers Union.
- 20 December – Cardiff becomes the official capital of Wales.
Arts and literature
- The Gold Medal for Architecture is introduced to the National Eisteddfod.
- Bertrand Russell retires to Plas Penrhyn, Penrhyndeudraeth.
- The Guild for the Promotion of Welsh Music is founded.
- National Eisteddfod of Wales (held in Pwllheli)
- National Eisteddfod of Wales: Chair – Gwilym Ceri Jones
- National Eisteddfod of Wales: Crown – W. J. Gruffydd
- National Eisteddfod of Wales: Prose Medal – William Thomas Gruffydd
- Emyr Humphreys wins the Somerset Maugham Award for Hear and Forgive.
- Kingsley Amis – That Uncertain Feeling
- Islwyn Ffowc Elis – Ffenestri Tua'r Gwyll
- (Edwin) Stuart Evans – Elegy for the Death of a Clown (poem)
- Gwilym Thomas Hughes – Ei Seren tan Gwmwl
- Elisabeth Inglis-Jones – The Story of Wales
- Dylan Thomas – A Child's Christmas in Wales (posthumously published)
- Louie Myfanwy Thomas writing as Jane Ann Jones – Plant y Foty
- R. S. Thomas – Song at the Year's Turning (poems)
- Richard Vaughan – Son of Justin
- Saunders Lewis – Siwan
- Grace Williams – Penillion
- Stanley Baker plays Richmond in Laurence Olivier's film of Richard III.
- The Constant Husband, starring Rex Harrison, with opening scenes filmed on location at New Quay and Aberaeron in 1954, includes some Welsh dialogue.
- January – First televised Welsh-language play, Cap Wil Tomos
- Cricket – Wilf Wooller becomes an England Test selector.
- Rugby Union
- BBC Wales Sports Personality of the Year – John Disley
- 22 January – Clive Griffiths, footballer
- 4 March – Joey Jones, footballer
- 2 May – Peter Sayer, footballer
- 22 May – Maggie Jones, Baroness Jones of Whitchurch, politician
- 9 June – Alun Pugh, politician
- 21 June (in Sunderland) – Janet Ryder, politician
- 22 June – Green Gartside, musician
- 2 August – Alun Davies, biologist
- 4 August – Steve Jones, marathon runner
- 8 August – Gordon Davies, footballer
- 3 September – Eirian Williams, snooker referee
- 12 October – Brian Flynn, footballer and manager
- 17 November – Amanda Levete, architect
- 7 December – Mihangel Morgan, author and academic
- Martyn Jones, painter
- 5 January – Douglas Marsden-Jones, Wales and British Lions rugby player, 61
- 25 January – Robert Dewi Williams, teacher, clergyman and author, 84
- 26 January – Gwilym Davies, Baptist minister, 75
- 29 January – Sir Rhys Rhys-Williams, politician, 89
- 19 March – Tom Evans, Wales international rugby player, 72
- 2 April – Billy O'Neill, Welsh international rugby player, 76
- 27 April – Ambrose Bebb, author, 60
- 19 May – Percy Bush, Wales international rugby union player, 75
- 21 June – Eric Evans, rugby union player and administrator, 61
- 13 July – Ruth Ellis, murderer, 28 (hanged)
- 28 August – Sir Lewis Lougher, businessman and politician, 83
- 28 September – Lionel Rees, airman, Victoria Cross recipient, 71
- 14 October – Harry Parr Davies, songwriter, 41
- 15 October – Thomas Jones (T. J.), founder of Coleg Harlech, 85
- 30 October – Bert Dauncey, Wales international rugby player, 83
- 1 November – Ronw Moelwyn Hughes, politician, 58
- 15 December – V. E. Nash-Williams, archaeologist, 58
- date unknown – Melbourne Johns, munitions worker and wartime secret agent, 55
- Nathan, Sara (2010-01-26). "Kylie's mother, the £10 Taff: Passenger lists of emigrants to Australia reveal Welsh roots of Mrs Minogue". Daily Mail. London. Retrieved 2015-11-05.
- "From humble beginnings... a history of the FUW". North Wales Daily Post. 2005-11-17. Retrieved 2015-11-05.
- Owen, O.L., ed. (1956). Playfair Rugby Football Annual 1955–56. London: Playfair Books Ltd.