Pseudonym of the French playwright Jean-Nicolas-Gustave van Nieuwenhuysen. He wrote numerous comedies, vaudevilles and opera librettos with the collaboration of Alfonse Royer. Together, they wrote the libretto for Verdi of Jérusalem, a remake of I Lombardi alla prima crociata.
Estimed artistically, Vaëz became director of both the Odéon and the Opéra Theatres. It was on the stage of the Opéra where on November 26th, 1847, Jérusalem was performed for the first time.