Pedro Alonso Lopez - 300+ murders
Where: Peru, Colombia and Ecuador
When: 1970s
By 1978, it's reckoned the "Monster of the Andes" had butchered 100 girls in Peru. Moving to Colombia then Ecuador he peaked with three kills a week. In 1980 he was arrested and began identifying 50 burial sites before a flash flood uncovered a mass grave. In an interview from his prison cell, he described himself as "the man of the century".