Rhyl (/rɪl/; Welsh: Y Rhyl, pronounced [ə ˈr̥ɨl]) is a seaside town and community in Denbighshire in Wales. The town lies on the north coast of Wales, at the mouth of the River Clwyd.

To the west is Kinmel Bay and Towyn, to the east Prestatyn, and to the south-east Rhuddlan and St Asaph. At the 2011 Census, Rhyl had a population of 25,149, with Rhyl–Kinmel Bay having 31,229. Rhyl forms a conurbation with Prestatyn and its two outlying villages, the Rhyl/Prestatyn Built-up area, whose 2011 population of 46,267 makes it North Wales's most populous non-city. Rhyl was once an elegant Victorian resort town, but suffered rapid decline around the 1990s and 2000s; attempts have been made to reverse this through county investment, equal to around £15 million from Denbighshire County, however, the outcomes have been perceived with varying levels of success. ^{[citation needed]}

Prior to being in Denbighshire since 1996, it was in the Clwyd district of Rhuddlan, and before that the historic county of Flintshire.

Early documents refer to a dwelling in the area named Ty'n Rhyl ("Rhyl croft"), and a manor house with that name still exists in the oldest part of the town. Its Welsh orthography has proved difficult for English writers to transliterate as Rhyl's opening voiceless alveolar trill is uncommon in the English language (represented in modern Welsh by the digraph 'Rh'). As such the name has appeared in English texts as Hulle (1292), Hul (1296), Ryhull (1301), Hyll (1506), Hull (1508), yr Hyll (1597), Rhil (1706), Rhûl (1749), Rhul (1773), Rhyll (1830) and Rhyl (1840).

The etymonic origin of the word Rhyl has been the subject of debate for more than a century. It has been suggested that it derives from a contraction of Yr Heol ("The Road"). However, this derivation is problematic as it is thought that no road of significance passed through the area before the name was already extant. Another suggested etymology is that the name is a hybrid of the unfamiliar English word "hill" and the Welsh definite article "yr" (Yr Hill, becoming Y Rhyl, and then just Rhyl in English). Although this is problematic as Rhyl is situated in a very flat area with no hills, it has been suggested that the original 'hill' was a piece of dry land relatively raised above the surrounding marshes (cors y rhyl). Another suggestion is that it could have referred to a now forgotten man-made structure, such as a motte outpost of Rhuddlan Castle guarding the mouth of the River Clwyd.

One etymology that gained popularity in the twentieth century suggests that the original dwelling of Ty'n Rhyl derived from Tŷ'n yr haul (House in the Sun/House of Sunshine). This may be an example of folk etymology, as Rhyl gained popularity as a summer destination for Welsh-speaking tourists and was advertised in English and Welsh as "Sunny Rhyl".

Rhyl has a number of Grade II listed buildings and landmarks. These include the Parish Church of St Thomas in Bath Street, which is listed as Grade II*. Others are the Midland Bank building, the railway station along with two signal boxes and the public telephone box on the up platform, the Royal Alexandra Hospital, the Sussex Street Baptist Church, Rhyl Town Hall, the Swan public house in Russell Road, the war memorial, and the Welsh Presbyterian Church in Clwyd Street.

Also notable is the Grade II listed Foryd Harbour Bridge, a blue bridge with distinctive bowstring girders built in 1932. Situated over the River Clwyd, it links Rhyl with Kinmel Bay.