Prince of Wales is a title traditionally given to the male heir apparent to the English, and later, the British throne. The title originated with the Welsh rulers of Gwynedd who, from the late 12th century, used it (albeit inconsistently) to assert their supremacy over the other Welsh rulers. However, to mark the finalisation of his conquest of Wales, in 1301, Edward I of England invested his son Edward of Caernarfon with the title, thereby beginning the tradition of giving the title to the heir apparent when he was the monarch's son or grandson. The title was later claimed by the leader of a Welsh rebellion, Owain Glyndŵr, from 1400 until 1415.

King Charles III created his son, William, Prince of Wales on 9 September 2022, the day after his accession to the throne, with formal letters patent issued on 13 February 2023. The title has become a point of controversy in Wales.

The first known use of the title "Prince of Wales" was in the 1160s by Owain Gwynedd, ruler of Kingdom of Gwynedd, in a letter to Louis VII of France. In the 12th century, Wales was a patchwork of Anglo-Norman Lordships and native Welsh kingdoms – notably Deheubarth, Powys and Gwynedd – competing among themselves for hegemony. As he was already the King of Gwynedd, Owain's aim in using the title in his letter to Louis was probably to claim pre-eminence over the other native Welsh rulers.

At the time, the word prince, deriving as it did from the Latin princeps, meant "first person, chief leader; ruler, sovereign." It was not until the 14th century that it came to mean "heir to the throne".

Following Owain's death in 1170 no other ruler, with the exception of Rhys ap Gruffydd of Deheubarth, is known to have adopted the title until 1245. Rhys used several titles, sometimes concurrently, and in two charters from the 1180s he is referred to as "Prince of Wales" or "Prince of the Welsh".

The title was revived in 1245 when Dafydd ap Llywelyn, ruler of Gwynedd, began using it in the final months of his reign. In the intervening years, Owen Gwynedd's successors in Gwynedd, including Dafydd, had, instead, adopted the titles "Prince of North Wales" or "Prince of Aberffraw and Lord of Snowdon".

However, it is in the reign of Llywelyn ap Gruffudd, Dafydd's nephew and successor in Gwynedd, that the title is consistently used over an extended period. From 1262 to his death in 1282, Llywelyn used no other style except 'Prince of Wales and Lord of Snowdon'. This was accompanied by Llywelyn making the Principality of Wales (encompassing Gwynedd, Deheubarth, Powys and parts of the Marches) a political reality. He had achieved this by significantly expanding his directly ruled territories into Mid- and South Wales and inducing all the other remaining native Welsh rulers to do him homage and acknowledge him as overlord by 1263. Additionally, Llywelyn developed governance structures which made his authority effective across the entire Principality of Wales, including in the territories of the Welsh rulers that owed him allegiance. The significance of these developments was marked by Henry III of England recognising Llywelyn's title and authority in the Treaty of Montgomery of 1267. As J. Beverley Smith has noted, his title "at once, acknowledged and proclaimed a status unique in Welsh political history".

Llywelyn's principality was destroyed as a result of the conquest of Wales by Edward I between 1277 and 1283, during which Llywelyn was killed in 1282. After his death, his brother, Dafydd, adopted Llywelyn's title and continued resistance for a few months. However, Dafydd was defeated and executed in 1283 and the principality was permanently annexed by Edward I.