Geoffrey Chaucer was a 14th century poet, living from circa 1343 to October 25, 1400. Chaucer is considered to be the greatest English poet of the Middle Ages, and was the first poet to be buried in the Poets' Corner of Westminiser Abbey.
His most famous work today is The Canterbury Tales, with other promenent works being Troilus and Crysede, The Book of the Dutchess, and The House of Fame. In the 14th century and prior, works that were considered "literary" were written entirely in Latin and French. Chaucer, however, wrote all of his works in Middle English vernacular, playing a vital role in transforming English into a literary language. Furthermore, writing in English made his works accessable to more than just the educated elite — the common man could read Chaucer's works.
By the time of his death, Chaucer had written ten major works and seventeen short poems. There are also several poems of unknown authorship that are presumed to have been written by Chaucer.