Short answers, pulled from the story.
Jacques-Louis David was a French Neoclassical painter born in Paris on the 30th of August 1748 and considered the preeminent painter of his era. He is important for transforming French art away from Rococo frivolity toward classical austerity, serving as arts director of the French Republic, and producing iconic works including The Death of Marat and The Coronation of Napoleon.
David was an active member of the Jacobin Club, a friend of Maximilien Robespierre, and a member of the National Convention where he voted for the execution of Louis XVI. He served on the Committee of General Security, organized large public festivals, and functioned as an effective arts dictator of the Republic, directing propaganda through painting and ceremonial design.
David was imprisoned twice following Robespierre's execution in 1794, serving much of his sentence at the Palais du Luxembourg. After his release he remarried his former wife in 1796 and later aligned himself with Napoleon, becoming the official court painter of the Empire after 1804.
The Death of Marat, completed in 1793, depicts David's friend Jean-Paul Marat assassinated in his bath by Charlotte Corday on the 13th of July 1793. David painted it in response to the National Convention's call to memorialize Marat as a revolutionary martyr, and it became the leading image of the Terror. The painting has been called the Pietà of the revolution.
David was classified as a regicide for having voted in the National Convention for the execution of Louis XVI. When the Bourbon monarchy was restored, this designation barred him from burial on French soil. He died on the 29th of December 1825 in Brussels, where his body was interred; it was moved to Brussels Cemetery in 1882.
Among David's most prominent pupils were Antoine-Jean Gros, who was later made a Baron by Napoleon's court, and Jean Auguste Dominique Ingres, who became the leading figure of the Neoclassical school and the primary rival of the emerging Romantic movement. David also trained Belgian artists including François-Joseph Navez and Ignace Brice during his years of exile in Brussels.