Mercury Communications was a national telephone company in the United Kingdom. The company was formed in 1981 as a subsidiary of Cable & Wireless to challenge the monopoly of British Telecom (BT) which was privatised in 1984. Mercury proved only moderately successful at challenging BT's dominance.

In 1997 the Mercury brand ceased to be and it was amalgamated into Cable & Wireless Communications. The consumer arm of the latter would eventually find itself bought out by the telecommunications firm NTL, now Virgin Media. Its name lives on through its original sponsorship of the Mercury Music Prize, now dubbed the 'Nationwide Mercury Prize' in light of its most recent sponsors. The majority of the media, however, have not taken to using this new name.