Physician, scientist and revolutionary are the biographical aspects that had better summarize the life of Jean-Paul Marat (1743-1793). Due to the role that he played during the French Revolution, his work as a physician and scientist, prior to the events of l789, was forgotten. Marat made important contributions in the area of optics and electricity reflected in numerous publications, as well as translating Newton's Opticks (1787). Well known for his radical and aggressive ideas, his political vocation led him to embrace the revolutionary cause after the events of the Bastille. His figure was not indifferent to his contemporaries; although considered a hero by the poorest citizens, aristocrats and bourgeois considered him a cruel extremist. During the last years of his life, he suffered a cutaneous disease, the diagnosis of which is still a matter of controversy. Proposed diagnoses include eczema, seborrheic dermatitis, scabies and dermatitis herpetica, among others. Marat was assassinated by Charlotte Corday in 1793, becoming a martyr for some segments of the society that worshiped his memory. He was a man with a complex and curious personality whose figure and legacy are still a matter of discussion.