William Stephens (16 May 1731 – 11 May 1803), known in Portugal as Guilherme Stephens, was an English entrepreneur and glass manufacturer who made a fortune in Portugal manufacturing lime after the 1755 Lisbon earthquake and then operating the Portuguese Royal Glassworks. He was a brilliant organiser, intelligent and charismatic, and he charmed dictators, queens and princes to become one of the richest industrialists in Europe.