Peter Kynaston Thomas, or P. K. as affectionately known by his colleagues, died on January 26, 2008, at the age of 81 years. He was a dominant figure in the field of peripheral neuropathy, with a career that spanned more than 5 decades and saw the introduction of electrophysiology, electron microscopy, immunology, and molecular biology, all of which he incorporated in his research into peripheral nerve diseases. He was equally at ease in the boardroom or editorial office, presiding over a meeting, or giving an after-dinner speech as he was at the bedside or laboratory. He served as president of the Association of British Neurologists and the European Neurological Society and was editor of Brain, the Journal of Neurology, and the Journal of Anatomy. His many honors included being named Commander of the British Empire and Fellow of University College in London.