Jacob van Maerlant (c. 1230–40 – c. 1288–1300) was the greatest Flemish poet of the 13th century and one of the most important Middle Dutch authors during the Middle Ages.
Van Maerlant was born near Bruges. He became sacristan of Maerlant, in the island of Oostvoorne, where he lived for some time, employed as a sexton, whence his surname "de Coster". Later he resided at Damme, near Bruges, where, according to tradition, he held the position of town clerk.
His early works are Middle Dutch translations of French romances. Jacob's most serious work in the field of romance was his Historie van Troyen (c. 1264), a poem of some forty thousand lines, translated and amplified from the Roman de Troie of Benoît de Sainte-Maure.
From this time Jacob rejected romance as idle, and devoted himself to writing scientific and historical works for the education and, enlightenment of the Flemish and Dutch nobility. His Heimelicheit der Heimelicheden (c. 1266) is a translation of the Secreta secretorum, a manual for the education of princes, ascribed throughout the Middle Ages to Aristotle. Van der Naturen Bloeme is a free translation of De natura rerum, a natural history in twenty books by a native of Brabant, Thomas of Cantimpré; and his Rijmbijbel is taken, with many omissions and additions, from the Historia scholastica of Petrus Comestor. He supplemented this metrical paraphrase of scripture history by Die Wrake van Jherusalem (1271) from Josephus. He also translated a Life of St. Francis (Leven van St. Franciscus) from the Latin of Bonaventure. Jacob's most extensive work is the Spiegel Historiael, a rhymed chronicle of the world, translated, with omissions and important additions, from the Speculum historiale of Vincent de Beauvais. It is dedicated to Count Floris V and was begun in 1283, but was left unfinished at the poet's death. Continuations were given by Philip Utenbroeke and Lodewijc van Velthem, a Brabant priest. He wrote three Arthurian works: Torec, which survives in the massive Lancelot-Compilatie;, and two romances based on the works of Robert de Boron, Historie van den Grale and Boec van Merline, which tell the stories of Joseph of Arimathea and Merlin.