Willem van Steenhuys, Lord of Flers (1558–1638) was a noble magistrate and diplomat in the Spanish Netherlands.

[1] In 1591 he married Margaretha (Marguerite) van (de) Cottignies, daughter of Lancelot, Lord of The Hague.

They had the following children: He obtained the degree of licentiate in law and on 7 June 1601 he was appointed a councillor of the Great Council of Mechelen, on 3 May 1611 councillor and master of requests of the Brussels Privy Council, and in 1613 commissioner in fiscal cases.

[2] In June 1617 and January 1619 he travelled to Antwerp and Leuven to investigate the publication of Corona Regia, a scandalous libel of James VI and I.

On 8 May 1622 he was appointed to the Council of State and in October of the same year he was discharged as a privy councillor and despatched to assist the Spanish delegation at the Diet of Regensburg (1623).