The Taff Vale Railway O3 class was a class of two 0-6-2T steam tank locomotives designed by Tom Hurry Riches, built by Kitson & Co. and introduced to the Taff Vale Railway in 1904. They were rebuilt with new boilers by the Great Western Railway (GWR) in 1930.
Both entered British Railways service in 1948, but neither lasted more than 3 months before being retired and scrapped. Both were withdrawn from the Cardiff Canton shed.