Girolamo Donzellini was born in 1513. He was a religious dissenter, a physician, and a bibliophile involved in the Medical Republic of Letters. He was put to death by the Venetian Inquisition in 1587, after being tried five times in his lifetime. Extending beyond an individual case study to a granular and probing account of the many connections between Venetian physicians and heterodox religious movements in the wake of the Protestant Reformation, this innovative monograph reveals the heretical networks of physicians in sixteenth-century Venice. In addition to Donzellini himself, the web of actors includes printers, scholars, women, and alchemists who were all committed to fighting against religious dogma and violence in a time and place when both were the order of the day. This book will appeal to researchers and students alike interested in the History of Medicine, the History of religious heterodoxy and tolerance, as well as the History of the Catholic Inquisition in Venice.