Antipope Benedict X

https://en.wikipedia.org/wiki/Antipope_Benedict_X

Benedict X (died 1073/1080), born Giovanni, was elected to succeed Pope Stephen IX on 5 April 1058, but was opposed by a rival faction that elected Nicholas II. He fled Rome on 24 January 1059 and is today generally regarded as an antipope.

He was a son of Guido, Lord of Poli who was the youngest son of Alberic III, Count of Tusculum, a member of the dominant political dynasty in the region at that time. Giovanni was a nephew of the notorious Pope Benedict IX, who was deposed in 1048. Benedict X reportedly later was given the nickname of Mincius (thin) due to his ignorance. His mother was present at his trial in April 1060.