Antipope Callixtus III or Callistus III (died before October 19, 1183) was Antipope

Antipope

An antipope is a person who opposes a legitimately elected or sitting Pope and makes a significantly accepted competing claim to be the Pope, the Bishop of Rome and leader of the Roman Catholic Church. At times between the 3rd and mid-15th century, antipopes were typically those supported by a...

 from September 1168 to 29 August 1178.

His real name was Giovanni, Abbot of Struma

Struma

The Struma was a ship chartered to carry Jewish refugees from Axis-allied Romania to British-controlled Palestine during World War II. On February 23, 1942, with its engine inoperable and its refugee passengers aboard, Turkish authorities towed the ship from Istanbul harbor through the Bosphorus...

. He was a strong and early supporter of Frederick Barbarossa, and also supported Antipope Victor IV, who made him a cardinal

Cardinal (Catholicism)

A cardinal is a senior ecclesiastical official, usually an ordained bishop, and ecclesiastical prince of the Catholic Church. They are collectively known as the College of Cardinals, which as a body elects a new pope. The duties of the cardinals include attending the meetings of the College and...

-bishop of Albano.

He was named successor to Antipope Paschal III

Antipope Paschal III

Antipope Paschal III was Antipope from 1164 to 20 September 1168.His real name was Guido of Crema. Paschal III was the second of the antipopes to challenge the reign of Pope Alexander III. In 1164, a small number of cardinals who had elected Victor IV met again to vote Paschal III as his successor...

 by a small number of schism

Schism (religion)

A schism , from Greek σχίσμα, skhísma , is a division between people, usually belonging to an organization or movement religious denomination. The word is most frequently applied to a break of communion between two sections of Christianity that were previously a single body, or to a division within...

atic cardinals. Callixtus was primarily a bargaining chip of Frederick to pressure Alexander III

Pope Alexander III

Pope Alexander III , born Rolando of Siena, was Pope from 1159 to 1181. He is noted in history for laying the foundation stone for the Notre Dame de Paris.-Church career:...

, and he had only limited geographical support. He resided in Viterbo

Viterbo

See also Viterbo, Texas and Viterbo UniversityViterbo is an ancient city and comune in the Lazio region of central Italy, the capital of the province of Viterbo. It is approximately 80 driving / 80 walking kilometers north of GRA on the Via Cassia, and it is surrounded by the Monti Cimini and...

.

Frederick, when it became politically expedient, after the defeat of Legnano

Battle of Legnano

The Battle of Legnano was fought on May 29, 1176, between the forces of the Holy Roman Empire, led by Emperor Frederick Barbarossa, and the Lombard League.-The Lombard League:...

, switched his backing to Alexander, in the 1177 Peace of Venice, abjuring his position on 29 August 1178. Callixtus eventually accepted the situation, submitting to Alexander in August 1178. After this he was named rector of Benevento

Benevento

Benevento is a town and comune of Campania, Italy, capital of the province of Benevento, 50 km northeast of Naples. It is situated on a hill 130 m above sea-level at the confluence of the Calore Irpino and Sabato...

, where he died a few years later.

There is also a pope with this name, Pope Callixtus III

Pope Callixtus III

Pope Callixtus III , né Alfons de Borja, was Pope from April 8, 1455 to his death in 1458.-Biography:...

.