Mr Leslie Williams was a blacksmith from Tonypandy, Rhondda, Wales. He was a professional boxer (bantamweight) and was traveling to the USA under contract for a series of boxing contests. He was traveling with a fellow Rhondda boxer, David Bowen, and was the better known of the two. His ring weight was 8 stones 10 pounds (122 pounds or 55.3 kg). He was regarded as a promising fighter.
Williams was married with one son. He and Bowen booked passage through the Cardiff office of Dean and Dawson, tourist and steamship agents, 67 St. Mary Street, Cardiff (ticket number 54636, £16 2s).
Williams' body was later recovered by the CS Mackay-Bennett (#14) and was buried at sea on 22 April 1912.