Childebert III (or IV), called the Just (French: le Juste) (c. 678/679 – 23 April 711), was the son of Theuderic III and Chrothildis (or Doda) and sole king of the Franks (694–711)[1].

He was seemingly but a puppet of the mayor of the palace, Pepin of Heristal, though his placita show him making judicial decisions of his own will, even against the Arnulfing clan.

His nickname has no comprehensible justification except possibly as a result of these judgements, but the Liber Historiae Francorum calls him a "famous man" and "the glorious lord of good memory, Childebert, the just king.

In 708, during his reign of sixteen years, the bishop of Avranches, Saint Aubert, founded the monastery of Mont-Saint-Michel supposedly at the urging of the Archangel Michael.

Upon his death on 23 April 711, southern Gaul began to grow independent: Burgundy under Bishop Savaric of Auxerre, Aquitaine under Duke Odo the Great, and Provence under Antenor.