Merovech (Latin: Meroveus or Merovius) (c. 415-457) is the semi-legendary founder of the Merovingian dynasty of the Salian Franks (although Chlodio may in fact be the founder), which later became the dominant Frankish tribe. He allegedly lived in the first half of the fifth century. His name is a Latinization of a form close to the Old High German given name Marwig, lit. "famed fight" (cf. māri "famous" + wīg "fight") compare modern Dutch mare "news, rumour", vermaard "famous" and vecht "fight". The first Frankish royal dynasty called themselves Merovingians ("descendants of Meroveus") after him.

There is little information about him in the later histories of the Franks. He was one of several barbarian warlords and kings that joined forces with the Roman general Aetius against the Huns under Attila on the Catalaunian fields in Gaul. Gregory of Tours only names him once as the father of Childeric I while putting doubt on his descent from Chlodio. Many admit today that this formulation finds its explanation in a legend reported by Fredegar. The Chronicle of Fredegar interpolated on this reference by Gregory by adding Merovech was the son of the queen, Chlodio's wife; but his father was a sea-god, bistea Neptuni. No other historical evidence exists that Merovech ever lived. Some researchers have noted that Merovech, the Frankish chieftain, may have been the namesake of a certain god or demigod honored by the Franks prior to their conversion to Christianity. It has been suggested Merovech refers to or is reminiscent to the Dutch river Merwede, nowadays part of the Rhine-Meus-Scheldt delta but historically a main subsidiary of the Rhine, in the area where, according to Roman historians, the Salian Franks once dwelled. Another theory considers this legend to be the creation of a mythological past needed to back up the fast-rising Frankish rule in Western Europe.