Coordinates: 51°44′N 3°08′W / 51.73°N 3.13°W / 51.73; -3.13

Abertillery (English pronunciation: /ˌæbərtɨˈlɛəri/; from Welsh: Abertyleri meaning "mouth of the river Tyleri", Welsh pronunciation: [abɛrtəˈleːrɪ]) is a town in the county borough of Blaenau Gwent in South Wales, 16 miles (26 km) north-west of Newport, originally on the Great Western Railway. Its population rose steeply during the period of mining development in South Wales, being 10,846 in the 1891 census and 21,945 ten years later. Lying in the mountainous mining district of the former counties of Monmouthshire and Glamorganshire, in the valley of the Ebbw Fach, the population was traditionally employed in the numerous coal-mines, ironworks and tin-plate works, now defunct. Further up the same valley are the mining townships of Nantyglo and Blaina.

Abertillery has a traditional-style town centre and several small schools. Today, its population numbers just over 11,000 and is thought to be declining. In 2003, Abertillery was found to have the cheapest houses in the United Kingdom, according to a survey by the Halifax, with an average price of only £37,872. Noted for its unspoilt rural scenery, Abertillery neighbours the small districts of Aberbeeg (Aber-bîg), Llanhilleth (Llanhiledd), Cwmtillery (Cwmtyleri), and Six Bells (Chwe Chloch).