William John Warner was born in Dublin on 1 November 1866. He took his professional name, Cheiro, from cheiromancy, the older word for palm reading, and by his own account learned palmistry, astrology and a form of Chaldean numerology during travels in India as a young man, though the details of that period rest largely on his own later telling. He later styled himself Count Louis Hamon, a title of disputed standing that nonetheless followed him through the rest of his career.
He built a substantial practice first in London, reading for a clientele that came to include Mark Twain, Oscar Wilde, Sarah Bernhardt, Mata Hari and, by his own account, Grover Cleveland, and used those readings to build a public reputation for predicting events as well as character. In his later years he moved to the United States and settled in Hollywood, where he continued to see clients, sometimes as many as twenty a day, and did some screenwriting on the side. He died there on 8 October 1936, following a heart attack, at sixty nine. The claims made for his early training in India, and much of the more sensational biographical material that circulated in his lifetime and after it, rest largely on his own accounts and on the mythology his public persona cultivated rather than on independent documentation, a pattern common to celebrity occultists of his era and worth noting rather than repeating uncritically.