Sir Peter Leonard Knight is a British physicist, professor of quantum optics and senior research investigator at Imperial College London, and principal of the Kavli Royal Society International Centre. He is a leading academic in the field of quantum optics and is the recipient of several major awards including the Royal Medal from the Royal Society and the Thomas Young Medal and Prize from the Institute of Physics. He is a former president of the Institute of Physics and Optica, the first non North American-based person to take the position. He is described as "one of the UK’s most influential scientists and leaders of scientific policy" by his peers.