Little Petey

Brazilian serial killer "little Petey" murdered over 40 people in prison. He began by murdering the gang that killed his girlfriend and then stabbing his father, who was in prison for killing his mother, during a visit. He was well liked because he was considered a sort of vigilante avenger, despite killing indiscriminately within the prison. Because of Brazil's odd sentencing laws, he could only serve a maximum of 30 years and is currently a YouTuber.