Johannes Ockeghem

Johannes Ockeghem (born Saint-Ghislain, near Mons, Belgium about 1410; died Tours, France, 6 February 1497), was the most famous composer of the Franco-Flemish School (from around the area which is now Belgium) in the last half of the 15th century, and is often thought of as the most important composer between Dufay and Josquin des Prez. He was an excellent choirmaster and teacher. He spent most of his life working for the French royal court.
Life.
The name Ockeghem is found with many different spellings in old documents. He was almost certainly born in the town of Saint-Ghislain. His native language was probably French.
Like many composers in this period, he started to learn about music by singing in a church choir, quite possibly in Saint-Ghislain and then in Mons. 
His first important job was working for Charles I, Duke of Bourbon in Moulins, (France). Then in 1451 he went to work for King Charles VII of France. By this time he was well known as a singer and composer. He worked for the royal court for more than 50 years and was rewarded with promotions and honours. Charles VII gave him important jobs. After Charles VII’s death Louis XI became king. He reigned for a long time and Ockeghem was in favour with the king. He often travelled with the king, visiting places such as Cambrai and even as far as Spain. He met famous people including the composers Dufay and Binchois. He also had other jobs in Paris.
Louis XI died in 1483. We do not kinow much about where Ockeghem went after that, but he probably died in Tours because that is where he left his will.
Music and influence.
Ockeghem was not a composer who wrote lots of music, but it is hard to tell as some of it might have got lost. There are 14 masses that survive and other vocal works. His "Missa pro Defunctis" is the earliest surviving polyphonic Requiem. Ockeghem based many of his masses on well-known tunes in a way that is called “cantus firmus technique”. Sometimes he put the borrowed tunes in the lowest part (he sang bass himself). This was rather unusual.
Ockeghem’s music influenced Josquin des Prez and other composers from Flanders and the Netherlands. 
When Ockeghem died Josquin Des Prez composed a motet called "La déploration de la mort de Johannes Ockeghem" in his honour. The music theorist Johannes Tinctoris described him as a great musician and one of the best singers he knew. Many younger composers used some of Ockeghem’s melodies as a base for their own compositions. In the Renaissance this kind of borrowing from the music ofc another composer was thought to be a great honour.