Colwyn Bay is a town, community, and seaside resort located in Conwy County Borough on the north coast of Wales. It overlooks the Irish Sea and lies within the historic county boundaries of Denbighshire. The settlement functions as a grouped community council covering Colwyn Bay, Old Colwyn, and Rhos-on-Sea, operating under the local government authority of Conwy County Borough Council.

The area's development accelerated significantly after the arrival of the railway in 1849, transforming it into a holiday town accessible from north-west England. The name may derive from Collwyn ap Tangno or the River Colwyn. Historical sites include associations with St Trillo and Ednyfed Fychan, while the Colwyn Bay Hotel served as Ministry of Food headquarters during World War II.

The town is defined by its 4.8-kilometre sandy beach, which is maintained by millions of tonnes of sand to remain permanently available regardless of tides. Key landmarks include Eirias Park, the Welsh Mountain Zoo, and the Victoria Pier, which closed in 2009 due to ownership disputes and partial collapse in 2017. The Porth Eirias Watersports Centre offers sailing and windsurfing tuition.

Colwyn Bay hosted the National Eisteddfod in 1910 and 1947, and its Victoria Pier was a popular venue for touring bands until 2008. The town is certified as a Fairtrade Town and has received multiple awards in the Wales in Bloom competition. It attracts visitors seeking seaside holidays, with nearby attractions including the Welsh Mountain Zoo and various wind farms visible from the shore.

The community had a population of 10,369 as of 2021, while the built-up area contained 29,275 residents. The economy is dominated by tourism, supported by its location on the A55 road and Colwyn Bay railway station. The climate features cool summers, mild winters, and Foehn winds, with the area holding the Welsh high temperature record for February at 18.7 °C from 2012 to 2019.