The last Merovingian king of the Frankish Kingdom was Childeric III. The Merovingians had ruled the Franks since the coronation of Clovis as the king 495 after the battle of Tolbiac, but the dynasty had suffered terribly in the Frankis civil wars, especially in the Brünhilde-Fredegunda feud, and after the last competent king, Dagobert I (d. 639), the Merovingian kings were little more than puppet regents.

The true powerholders of the Frankish Kingdom were the mayors of the palace (Latin: majordomus) who acted effectively as prime ministers and commanders-in-chief. In the end the majordomus of Neustria, Pepin the Short, arranged a coup d'etat and deposed the last Merovingian king Childeric III.

He was shaved bald - the Franks considered the long hair of the kings as the symbol of regency - and sent to a monastery. Pepin was crowned as the King of Franks in 752. His son Charles was later to be known as Emperor Charlemagne.

More Info: en.wikipedia.org