The miners' strike of 1984–1985 was a major industrial action within the British coal industry in an attempt to prevent colliery closures. It was led by Arthur Scargill of the National Union of Mineworkers (NUM) against the National Coal Board (NCB), a government agency. Opposition to the strike was led by the Conservative government of the Prime Minister, Margaret Thatcher, who wanted to reduce the power of the trade unions.

The NUM was divided over the action and many mineworkers, especially in the Midlands, worked through the dispute. Few major trade unions supported the NUM, primarily because of the absence of a vote at national level. Violent confrontations between flying pickets and police characterised the year-long strike, which ended in a decisive victory for the Conservative government and allowed the closure of most of Britain's collieries. Many observers regard the strike as "the most bitter industrial dispute in British history". The number of person-days of work lost to the strike was over 26 million, making it the largest since the 1926 general strike. The journalist Seumas Milne said of the strike, "it has no real parallel – in size, duration and impact – anywhere in the world".: ix The NCB was encouraged to gear itself towards reduced subsidies in the early 1980s. After a strike was narrowly averted in February 1981, pit closures and pay restraint led to unofficial strikes. The main strike started on 6 March 1984 with a walkout at Cortonwood Colliery, which led to the NUM's Yorkshire Area's sanctioning of a strike on the grounds of a ballot result from 1981 in the Yorkshire Area, which was later challenged in court. The NUM President, Arthur Scargill, made the strike official across Britain on 12 March 1984, but the lack of a national ballot beforehand caused controversy. The NUM strategy was to cause a severe energy shortage of the sort that had won victory in the 1972 strike. The government strategy, designed by Margaret Thatcher, was threefold: to build up ample coal stocks, to keep as many miners at work as possible, and to use police to break up attacks by pickets on working miners. The critical element was the NUM's failure to hold a national strike ballot.: 71–95 The strike was ruled illegal in September 1984, as no national ballot of NUM members had been held. It ended on 3 March 1985. It was a defining moment in British industrial relations, the NUM's defeat significantly weakening the trade union movement. It was a major victory for Thatcher and the Conservative Party, with the Thatcher government able to consolidate their economic programme. The number of strikes fell sharply in 1985 as a result of the "demonstration effect" and trade union power in general diminished. Three deaths resulted from events related to the strike.

The much-reduced coal industry was privatised in December 1994, ultimately becoming UK Coal. In 1983, Britain had 174 working pits, all of which had closed by the end of 2015. Poverty increased in former coal mining areas, and in 1994 Grimethorpe in South Yorkshire was the poorest settlement in the country.