St. Benno wasn’t violently killed, making him the most successful saint on the list. He did, however, have to deal with Saxons, excommunications, disappearances, and the terrifying-sounding antipope. One version of Wikipedia stated that if the pope and the antipope ever met, the world would end. Sounds legit.
Benno opposed Pope Gregory, who is also a saint and excommunicated Holy Roman Emperor Henry IV not once but twice. King Henry responded by appointing an antipope– Clement III, “who reigned in opposition to four successive popes in the anti-imperial line: Gregory VII, Victor III, Urban II, and Paschal II.” Anti-Imperial! This guy is practically Darth Vader! And he was A-Ok with papal concubines! He was a fun guy, according to Benno!
Nevertheless, King Henry imprisoned Benno for supporting the Saxon insurrection of 1073. Benno repented, and promised to side with the king’s forces, but he didn’t. After leaving prison, he confesses his sins to Antipope Clement III and was forgiven for his sins. There he also promised to try to make peace with the Saxons but instead went to Pope Urban and treated him as the rightful pope. Urban had taken over from Gregory after the brief rule of a very reluctant Victor III, who was not only forced into marriage, but also forced into popehood. Popedom. Whatever.
Then St. Benno drops out of the historical record, mostly. In one surviving anecdote, he reacts to the news that Henry IV has been excommunicated by throwing the keys to the cathedral into the Elbe. Legend says that the keys were found in the belly of a fish and were returned.
See? Right in there.
A note on antipopes: there have been more antipopes than I would have expected, mostly in the 1000’s, when people just couldn’t get their shit together. Currently there is one living in Kansas. His website now-defunct website Vatican in Exile indicated that he had recently started a convent. Pope Michael’s faceook page appears active, and he has his own wikipedia page now. Nuns have been excommunicated for heresy before, once as recently as 2007, but I think as the everyday Catholic you’d be safe just to sign up and try it out for a while.