Lieven de Key (1560 — 17 July 1627) was a famous Dutch renaissance architect in the Netherlands, mostly known today for his works in Haarlem.
De Key was born in Ghent, and was already a well known architect when the Haarlem council asked him to become city architect in 1592 to succeed Wouter den Abt. He brought to Haarlem the same Dutch renaissance style that Hendrick de Keyser brought to Amsterdam. Everything attributed to him or his followers, whether a building, a doorway, or merely a gable stone, is considered a rijksmonument today.
The reason so many buildings in Haarlem can be attributed to him is because Haarlem had suffered a severe fire in 1576 that destroyed a third of the city, and plans were underway for large city projects when he was appointed city architect. Before working in Haarlem and Leiden, De Key had worked in London from 1580-1591. He died in Haarlem, aged about 77.