Which is a little unfair, because he wrote several other novels, along with plays, short stories, and poetry. But hey, if you're going to be famous for just one thing, you can do worse than writing what is often regarded as the first modern novel, the most famous Spanish language novel, and the most translated book in the world apart from The Bible.
Miguel de Cervantes Saavedra (circa 29 September 1547 22 April 1616) actually had quite an interesting life. He was born in Alcalá de Henares, Spain, the son of a poor barber-surgeon, some time around late September 1547; given the custom of the time of naming children after the saint whose feast day they were born on, it was likely on the 29th, the feast day of Saint Michael the Archangel. He seems to have picked up a bit of education without learning the Latin that he needed to make it fully respectable, and then in 1569 he went off to Rome to further his artistic education, landing a job working for a cardinal. In 1570 he joined the Spanish marines, which meant that in 1571, he fought in the historic Battle of Lepanto — where he took three gunshot wounds, one of which left his left arm useless for the rest of his life. (So, yes, he was an authentic Warrior Poet.) Still, he continued to serve as a soldier for a few years (suggesting that he was a bit of a Handicapped Badass), before he was captured by Ottoman pirates in 1575 and Made a Slave in Algeria for five years.
Fortunately, he was then ransomed, and returned to Spain. He then launched his literary career, while supporting himself by working as a royal tax collector and a purchasing agent for the Spanish Armada — which led to him spending a short stint in prison on suspicion of involvement in some kind of fraud. He published the first part of Don Quixote in 1605, and the second in 1615. He died in 1616, probably of type 2 diabetes caused by cirrhosis of the liver (though he doesn't seem to have been an alcoholic).
Cervantes is considered hugely important in the history of Spanish literature, alongside his contemporary and Sitcom Arch-Nemesis, Lope de Vega. Hence, he tends to show up in a lot of Historical, Alternate History, and Time Travel stories, from Man of La Mancha to The Ministry of Time. His influence tends to be compared to that of his close contemporary, William Shakespeare, on English.