ABERTILLERY, an urban district in the western parliamentary division of Monmouthshire, England, 16 m. N.W. of Newport, on the Great Western railway. Pop. (1891) 10,846; (1901) 21,945. It lies in the mountainous mining district of Monmouthshire and Glamorganshire, in the valley of the Ebbw Fach, and the large industrial population is mainly employed in the numerous coal-mines, ironworks and tinplate works. Farther up the valley are the mining townships of Nantyglo and Blaina, forming an urban district with a population (1901) of 13,489.