Baron Joseph (Josse) Marie Honoré Charles Mertens de Wilmars (22 June 1912 – 1 August 2002) was a Belgian jurist who became a member of the European Court of Justice and then its sixth President.
Mertens de Wilmars was born in Sint-Niklaas, into a family of brewers.
One of his brothers was the psychiatrist Charles Mertens de Wilmars.
He was in favour of European unity, and attended the Congress in the Hague in 1948.
He became a member of the European Court of Justice in 1967, and served as its sixth President from 1980 to 1984.