Jean-Jacques Manget (or Johann Jacob Mangetus) (1652–1742) was a Genevan physician and writer. He was an assiduous compiler of previous medical literature.
He was born in Geneva, the son of a merchant. He graduated as a physician at the University of Valence in 1678. Later he became the Dean of the Valence medical faculty. Frederick III, Elector of Brandenburg made Manget his personal physician in 1699.
Manget wrote in particular a major treatise on the bubonic plague. He is known also for a large collection of alchemical works, the Bibliotheca Curiosa Chemica, from 1702.