Jan, a distinguished scholar and critic, was born at Antwerp in 1560. His father was a Fleming, but his mother, whose name was Tishem, was an Englishwoman, and able, from her own knowledge of the classics, to instruct her son in them. Being obliged to fly Holland for siding with the Reformed faith, Gruter's family came to England, and the young Gruter, after studying for some years at Cambridge, returned to his native land, and graduated at Leyden. After this he seems to have taught successively at Rostock, Wittenberg, and Heidelberg, in which last city he resided till his death in 1627, despite of tempting offers of professorships in France, Denmark, and Italy. It is not known what chair he held in Heidelberg, but he was also conservator of the university library. His knowledge of bibliography enabled him to amass a large private library, which, however, he lost in the memorable siege of Heidelberg in 1622.

Gruter at one time enjoyed a vast reputation for learning, and there is no doubt that he was as good a scholar as a man of solid faculties and unwearied industry can alone be. But though his erudition was great, his mental power, beyond the mere faculty of acquisition, seems to have been small; and, accordingly, we do not find that he has made any valuable contribution to any department of scholarship. Besides editions of some of the Latin classics which involved him in highly indecent controversies with Pareus and others of his contemporaries, Gruter compiled a most valuable work, published at Heidelberg in 1601, under the title of Inscriptiones antiquae totius orbis Romani. Gruter is said to have written a book every month, but the entire list of his works preserved in Nieuron only comprises thirty-two. These, as has been already mentioned, are chiefly the later Latin classics, and possess but little critical value.