Berengar I was a ninth-century nobleman of East Francia, a son of Gebhard I von Wetterau, Count of Lahngau, and younger brother of Udo II von Wetterau of Neustria. He and his brother were created Margraves of Neustria by Charles the Bald in 861. Charles' patronage of the family provoked the jealousy of the Rorgonids, the most powerful family local to Neustria and then controlling the ducatus Cenomannicus (Maine). In 865, they allied with Saloman of Brittany and attacked the brothers. Charles, to attain peace, took the march back and gave it to Gauzfrid, a Rorgonid.