Victor IV (died after April 1139) was an antipope for a short time in 1138.
He was born in Ceccano as Gregorio Conti. Pope Paschal II created him cardinal-priest of SS. XII Apostoli ca. 1102, but in 1112 deposed him and replaced in his title, because he had severely criticised (together with cardinal Robert of S. Eusebio, also subsequently deposed) Paschal's policy towards the emperor Henry V. He was restored as cardinal only by Callistus II in 1122/23. In the papal election, 1130 he joined the obedience of Antipope Anacletus II (1130–38) and after his death he was chosen as his successor in March 1138. However, through the influence of Bernard of Clairvaux he was induced two months afterwards to make his submission to Pope Innocent II (1130–43). Innocent II initially restored him as cardinal of SS. Apostoli, but in the Second Lateran Council in April 1139 all the former adherents of Anacletus II were condemned and deposed. Then he retired to the priorate of S. Eusebio in Fontanella. The date of his death is not recorded; his successor in the title of SS. Apostoli appears for the first time on January 4, 1157.