https://en.wikipedia.org/wiki/Reginar,_Duke_of_Lorraine

Reginar I Longneck[1] [2] was the Duke of Lorraine from 910 until his death. He stands at the head of the clan of Reginarids, an important Lotharingian noble family.

He was the son of Gilbert, Count of the Maasgau, and a daughter of Lothair I of whom the name is not known .

He succeeded his father in the Maasgau and was the lay abbot of Echternach between 897 and 915, of Maastricht from before May 898, and of Stablo and Malmedy between 900 and 902.

He was the Count of Mons when in 870 he and Franco, Bishop of Liège, led an army against the Vikings in Walacria. He, as Duke of Hesbaye and Hainault, and Radbold led a Frisian army against the forces of Rollo a little later, but were forced back to his fortresses.

In an 877 capitulary from Quierzy, he appears alongside his father as one of the regents of the kingdom during Charles the Bald's absence on campaign in Italy. A Reginar appears at the Siege of Paris in 886, but this may be an uncle or nephew. The name "Reginar" or "Reginhar" was commonplace in his family.