Charles Martel (/mɑːrˈtɛl/; c. 688 – 22 October 741), Martel being an Old French sobriquet meaning "The Hammer", was a Frankish political and military leader who, as Duke and Prince of the Franks and Mayor of the Palace, was the de facto ruler of the Franks from 718 until his death. He was a son of the Frankish statesman Pepin of Herstal and a noblewoman named Alpaida. Charles successfully asserted his claims to power as successor to his father as the power behind the throne in Frankish politics. Continuing and building on his father's work, he restored centralized government in Francia and began a series of military campaigns that re-established the Franks as the undisputed masters of all Gaul. According to the contemporary Liber Historiae Francorum, Charles was "a warrior who was uncommonly ... effective in battle".

Charles gained a victory against an Umayyad invasion of Aquitaine at the Battle of Tours, and Charles is credited as an important factor in curtailing the spread of Islam in Western Europe. Alongside his military endeavours, Charles has been traditionally credited with an influential role in the development of the Frankish system of feudalism.

At the end of his reign, Charles divided Francia between his sons, Carloman and Pepin; Pepin became the first king of the Carolingian dynasty. Pepin's son Charlemagne, grandson of Charles, extended the Frankish realms and became the first emperor in the West since the Fall of the Western Roman Empire.

Charles, nicknamed "Martel" ("the Hammer") in later chronicles, was a son of Pepin of Herstal and his mistress, possibly second wife, Alpaida. He had a brother named Childebrand who later became the Frankish dux (that is, duke) of Burgundy. Charles was a great-grandson of Arnulf of Metz.

Older historiography commonly describes Charles as "illegitimate", but the dividing line between wives and concubines was not clear-cut in 8th-century Francia. It is likely that the accusation of "illegitimacy" derives from the desire of Pepin's first wife Plectrude to see her progeny as heirs to Pepin's throne.

By Charles's lifetime the Merovingians had ceded power to the mayors of the palace who controlled the royal treasury, dispensed patronage, and granted land and privileges in the name of the figurehead king. Pepin of Herstal had united the Frankish realm by conquering Neustria and Burgundy. Pepin was the first to call himself Duke and Prince of the Franks, a title later taken up by Charles.

In December 714 Pepin died. A few months before his death and shortly after the murder of his son Grimoald the Younger, he had taken the advice of Plectrude to designate as his sole heir Theudoald, his grandson by Grimoald. This was immediately opposed by the Austrasian nobles because Theudoald was a child of only eight years of age. To prevent Charles using this unrest to his own advantage, Plectrude had him imprisoned in Cologne, the city which was intended to be her capital. This prevented an uprising on his behalf in Austrasia, but not in Neustria.

Pepin's death occasioned open conflict between his heirs and the Neustrian nobles who sought political independence from Austrasian control. In 715 Dagobert III named Raganfrid as mayor of the palace over Neustria and Burgundy. On 26 September 715, Raganfrid's Neustrians met the young Theudoald's forces at the Battle of Compiègne. Theudoald was defeated and fled back to Cologne. Before the end of the year, Charles had escaped from prison and was acclaimed mayor of the palace over Austrasia. Dagobert died in 715, and the Neustrians proclaimed Chilperic II, the cloistered son of Childeric II, as king.