John Lorimer Campbell is a British YouTuber and retired nurse educator who has posted YouTube videos commenting on the COVID-19 pandemic since January 2020 on his channel, Dr. John Campbell. Initially, his videos received some praise, but later veered into misinformation, such as the suggestion that deaths from COVID-19 have been over-counted, repeated false claims about the use of the anti-parasitic drug ivermectin as a COVID-19 treatment, and misleading commentary about vaccine safety. His videos have been viewed more than 550 million times.