Willem van Haecht was a Flemish painter best known for his pictures of art galleries and collections.

Willem van Haecht was born in Antwerp as the son of the landscape painter Tobias Verhaecht. Tobias Verhaecht was a prominent painter who had been the first teacher of Peter Paul Rubens. Willem was a pupil of his father.

He worked in Paris from 1615 to 1619, and then travelled to Italy for about seven years. Van Haecht became a master in Antwerp's guild of St. Luke in 1626 and from 1628 onwards was the curator of the art collection owned by Cornelis van der Geest.

This collection is represented in allegorical terms in the Gallery of Cornelis van der Geest (1628; Rubenshuis, Antwerp). The left side of the painting includes various portraits of contemporaneous figures, including (from the left) Infanta Isabel Clara of Spain, Archduke Albert of Austria, Peter Paul Rubens, Prince Władysław Vasa of Poland (who visited van der Geest's Gallery in 1624, with black hat) and the host showing a picture, as well as many famous paintings such as Paracelsus by Quentin Matsys.

Alexander the Great Visiting the Studio of Apelles (ca. 1630, Mauritshuis) is another gallery painting by van Haecht. It has significant documentary evidence as it is believed it is an idealised image of elements drawn from Rubens' collection.