Stephen VI (VII) the Pope from 896-7 who disinterred his predecessor Formosus and brought his corpse to trial. He declared all of Formosus’ acts null and void, stripped the corpse of its Papal garments, mutilated it and later had it thrown into the river.
Sergius III the Pope from 904-11. This Pope attained the papacy by assassinating his predecessor Leo V and his rival Christopher. His child through union with a noblewoman named Marozia (his mistress)became Pope John XI.
Pope John XII (955-63) was “a coarse, immoral man, whose life was such that the Lateran was spoken of as a brothel, and the moral corruption in Rome became the subject of general odium…” (The Catholic Encyclopedia, Vol. VI, p. 426).
Alexander VI (1492-1503) was rebuked by Pope Pius I for having 4 children by Vanozza dei Catanei – two of the most famous being Lucretia and Cesare Borgia. Lucretia was married off by this infamous Pope no less than 3 times. Of lesser consideration is the fact that he attained his papal throne through bribery.