The title Baron Monthermer was created twice in the Peerage of England. The first creation was for Ralph de Monthermer who was summoned to parliament on 4 March 1309. After the death of the second baron, his heiress Margaret inherited the barony. On her death, her son, John de Montacute, succeeded her in the barony and in 1397 he became Earl of Salisbury with which title the barony became united.