Garibald I (also Garivald; Latin: Garibaldus; born 540) was Duke (or King) of Bavaria from 555 until 591. He stands at the head of the Agilolfings and the Bavarian Dynasty that ruled the Kingdom of the Lombards.
After the death of the Merovingian king Theudebald of Austrasia, his successor Chlothar I had "begun to have intercourse with" his widow Waldrada (531–572), daughter of the Lombard king Wacho. Chlothar's bishops objected, so he gave Waldrada to Garibald to marry in 556. Not only did this grant Garibald prestige, but it created lasting political ties between the Bavarii and the Lombards of Pannonia and Bohemia. This would have consequences after the Lombards moved into Italy in 568.
Some time before 585, the Merovingian court attempted to bind Duke Garibald more closely to their interests by arranging a marriage between his daughter Theodelinda and King Childebert II of Austrasia. At the same time the Merovingians were attempting to normalise relations with Authari, the Lombard king, by arranging a marriage between Childebert's sister and Authari. Both these proposals fell through. The offended Authari was engaged to Theodelinda in 588. Fearing an anti-Frankish axis, the Franks sent an army into Bavaria. Garibald's children Gundoald and Theodelinda fled to Italy. Authari married Theodelinda in May 589 and named his brother-in-law, Gundoald, Duke of Asti. In 590, the Franks invaded Lombardy with help from Byzantium, but were defeated.