Lorenz Heister (Latin: Laurentius Heister) (19 September 1683 – 18 April 1758) was a German anatomist, surgeon and botanist born in Frankfurt am Main.
From 1702 to 1706 Heister studied at the Universities of Giessen and Wetzlar, afterwards relocating to Amsterdam, where he studied anatomy under Frederik Ruysch (1638–1731). In the summer of 1707, he was an assistant physician in field hospitals at Brussels and Ghent during the War of the Spanish Succession. He then traveled to Leiden, where he studied anatomy under Bernhard Siegfried Albinus (1653–1721) and Govert Bidloo (1649–1713), also attending Hermann Boerhaave’s lectures on chemistry and ocular diseases. In 1708 he earned his doctorate from the University of Harderwijk, and in the summer of 1709, rejoined the Dutch military as a field surgeon during the Siege of Tournai. Shortly afterwards, he distinguished himself in treatment of the wounded from the Battle of Malplaquet.
In 1711 he was appointed professor of anatomy and surgery at the University of Altdorf, and from 1720, was a professor of anatomy and surgery at Helmstedt, where he remained for rest of his life. During his tenure at Helmstedt, he also taught classes in botany and practical medicine. In 1730 he was elected a Fellow of the Royal Society.