Laurens Theodorus Gronovius (June 1, 1730 – August 8, 1777), also known as Laurentius Theodorus Gronovius or as Laurens Theodore Gronow, was a Dutch naturalist who was born in Leiden. He was the son of botanist Jan Frederik Gronovius (1686–1762).
Throughout his lifetime Gronovius amassed an extensive collection of zoological and botanical specimens, and is especially remembered for his work in ichthyology, where he played a significant role in the classification of fishes. In 1754 he published the treatise Museum ichthyologicum, where he described over 200 species of fish. He is also credited with developing a technique for preservation of fish skins. Today, a number of these preserved specimens are kept in the Natural History Museum in London.
In 1762 he published the second edition of his father's Flora Virginica exhibens Plantas.