William Crawshay II (27 March 1788 – 4 August 1867) was the son of William Crawshay I, the owner of Cyfarthfa Ironworks in Merthyr Tydfil, south Wales.
William Crawshay II became an ironmaster when he took over the business from his father. He was known as the 'Iron King'. He was responsible for the building of Cyfarthfa Castle (now a school and museum) in the 1820s and also of the present Caversham Park in Oxfordshire (now Berkshire) in 1850. He retired to Caversham in 1847, and his son, Robert Thompson Crawshay, carried on the South Wales business.