John Stewart (born 1950) is a British environmental campaigner who specializes in transport issues and noise pollution. In the 1980s and 1990s, he helped coordinate a national network of community groups that successfully campaigned against the British government's then-£23-billion road-building programme. Later, Stewart led the successful campaign against a third runway at Heathrow Airport. He has several times been recognized as one of Britain's most effective environmental campaigners.