Martin I of Sicily, called "The Younger", was King of Sicily from 1390 to 1409.
Martin's father was the future King Martin I of Aragon, and his grandparents were King Peter IV of Aragon and Eleanor of Sicily. In February, 1392 he married Maria of Sicily, born in 1362/1363. In 1392 he returned with Maria to Sicily with a military force and defeated a group of opposing barons. In 1394 the couple had their only son Peter, crown prince of Sicily, who died in 1400. He ruled Sicily jointly with Maria until her death at Lentini on 25 May 1401. At that time, he repudiated the Treaty of Villeneuve (1372) and ruled Sicily alone. After his death in 1409 in Cagliari, Sardinia, his father, by then king of Aragon, ruled Sicily as Martin II.
Martin the Younger led the troops in the conquest of Sardinia in 1409, decisively defeating the ruler of Arborea at the Battle of Sanluri just before his own death.