The worst mining accident in the United Kingdom's history took place when an explosion resulted in 440 deaths at the Universal Colliery in Senghenydd, Wales.

A mining accident is an accident that occurs during the process of mining minerals or metals. Thousands of miners die from mining accidents each year, especially from underground coal mining, although accidents also occur in hard rock mining. Coal mining is considered much more hazardous than hard rock mining due to flat-lying rock strata, generally incompetent rock, the presence of methane gas, and coal dust. Most of the deaths these days occur in developing countries, and rural parts of developed countries where safety measures are not practiced as fully. A mining disaster is an incident where there are five or more fatalities.

The Senghenydd colliery disaster, also known as the Senghenydd explosion, occurred at the Universal Colliery in Senghenydd, near Caerphilly, Glamorgan, Wales, on 14 October 1913. The explosion, which killed 439 miners and a rescuer, is the worst mining accident in the United Kingdom. Universal Colliery, on the South Wales Coalfield, extracted steam coal, which was much in demand. Some of the region's coal seams contained high quantities of firedamp, a highly explosive gas consisting of methane and hydrogen.

Universal Colliery was a coal mine located in Senghenydd in the Aber Valley, roughly four miles north-west of the town of Caerphilly. It was in the county borough of Caerphilly, traditionally in the county of Glamorgan, Wales.

Senghenydd is a former mining village in the community of Aber Valley in South Wales, approximately four miles northwest of the town of Caerphilly. Historically within the county of Glamorgan, it is now situated in the county borough of Caerphilly. In the United Kingdom Census 2001, the population of the Aber Valley was 6,696. The wind farm proposed in 2023 would see the village surrounded by turbines up to 200 metres high.