Charles Martel (Charles The Hammer) was the father of Pepin the Short, and the grandfather of Charlemagne. He was born in 689 and died in 741.
He was the illegitimate son of Pepin of Herstal, Mayor of the Palace to the Merovingian King Theodoric. The Mayor of the Palace was a hereditary office, one whose occupant was the real head of the government.
When Pepin of Herstal died, his widow Plectrude became regent for one of his grandsons. Charles Martel was imprisoned by Plectrude, but escaped and led an army to fight the rebelling province of Neustria. By 719 Charles had established himself as the ruling power of the kingdom -- though the king, Chilperic II, was still the nominal ruler.
Charles Martel expanded the Frankish kingdom into Neustria, Burgundy, Aquitaine, and Provence. He is famous for defeating the invading Spanish Muslim army at the Battle of Poitiers in 732.
He divided the kingdom when he died between his sons Pepin the Short and Carloman.