Laurens Janszoon Coster (ca. 1370, Haarlem, the Netherlands – ca. 1440), or Laurens Jansz Koster, was one of the early European printers. He was an important citizen of Haarlem and held the position of sexton (Koster) of Sint-Bavokerk. He is mentioned in contemporary documents as an assessor (scabinus), and as the city treasurer. He probably perished in the plague that visited Haarlem in 1439-1440; his widow is mentioned in the latter year.
There are no works certainly printed by Laurens, however there is a tradition that, sometime in the 1420s, he was carving letters from bark for the amusement of his grandchildren, and observed that the letters left impressions on the sand. He is said to have printed several books including Speculum Humanae Salvationis with several assistants including Johann Fust, and it was Fust who, when Laurens was nearing death, stole his presses and type and took them to Mainz where he entered partnership with Johann Gutenberg.
The earliest description of this story dates from 1568 in a history by Hadrianus Junius, a Dutch intellectual. If true, he would have been the first European to invent the movable type printing press, a feat generally ascribed to Gutenberg about a decade after Coster's death. Either way, he is somewhat of a local "hero", and apart from a statue on the Grote Markt his name can be found in many places in the city.
However, there is one support for the claim that Coster might be the inventor. In the Kölner Chronik of 1499 Ulrich Zell, the first printer of Cologne, mentions that printing was performed in Mainz of 1450, but that before already some type of printing of lower quality occurred in The Netherlands. The name of Coster is not mentioned in that article.