Piers Richard Corbyn (born March 10, 1947) is a British weather forecaster, anti-vaccine activist, conspiracy theorist, and former politician.

Born in Wiltshire, Corbyn was raised in Shropshire where he attended Adams' Grammar School. He was awarded a first class BSc degree in physics from Imperial College London in 1968 and a postgraduate MSc in astrophysics from Queen Mary College, University of London, in 1981. Corbyn was a member of the Labour Party and served as a councillor in the London Borough of Southwark from 1986 to 1990. He is the elder brother of former Labour Party leader Jeremy Corbyn. He left Labour due to his opposition to the Iraq War.

Corbyn ran a weather monitoring company called WeatherAction in the 1990s and gained some prominence in the media for his predictions and, later more so, for his rejection of the scientific consensus on climate change.

Throughout the COVID-19 pandemic, he was a prominent proponent of conspiracy theories. He described SARS-CoV-2 as a "hoax", frequently campaigned against lockdowns and against COVID-19 vaccines, and described COVID-19 vaccines as dangerous. Corbyn was arrested on several occasions for taking part in protests against public health laws, and for calling on supporters to commit violent acts against members of Parliament.