Joseph Hubertus Pilates (1883-1967) was a German-born physical fitness instructor who gave his name to the Pilates method of exercise. Living in England at the outbreak of the First World War, he was interned as an enemy alien and transferred from Lancaster to Knockaloe on 12 September 1915, where he is believed to have been held in Camp 4. He was repatriated to Germany in March 1919.

The documented trace of his years at Knockaloe is slight. The one firm camp record is the Camp 4 newspaper, the Lager Zeitung of 25 January 1917, which names him as referee at a boxing match, disqualifying one contestant for ignoring his instructions. Beyond this, the record of his time on the Island rests largely on his own later recollections.

Much of the popular Pilates origin story is legend rather than record. The founding tale of his equipment, that he worked as a hospital orderly and rigged springs from internees' bed frames, is unproven. The Knockaloe Charitable Trust finds no evidence of hospital work, and his biographer Javier Perez Pont found no such springs on the camp beds. The story that he took inspiration from watching cats comes from his own interview with Robert Wernick in Sports Illustrated in February 1962, which places the cats at the camp on the Isle of Man. That some of those cats would have been Manx is a reasonable inference, but the sources say only "cats", never "Manx cats", and the familiar claim that he copied his movements from Manx cats goes beyond anything the record supports.