Pope Stephen VII
Pope Stephen VII presided over the Synod Horrenda in 896 AD, when he took the body of his predecessor Pope Formosus and put him on trial for heresy. Since Formosus was dead, there was no stopping Stephen, and he ended up throwing the body into the Tiber river. Soon after the Synod, an earthquake toppled the Lateran basilica, which led people to think that Stephen VII was an antipope. He ended up being strangled by a rival faction that same year.