This article refers to the former Cardinal Gregorio Conti, antipope in 1138. For the antipope from 1159–1164, see Antipope Victor IV

Antipope Victor IV, born Gregorio Conti was chosen by a party in succession to the antipope Anacletus II on March 13, 1138, but through the influence of Bernard of Clairvaux was induced two months afterwards to make his submission to Innocent II. Before his election, he was known as Cardinal Gregorio Cardinal Conti.