7. Dennis Nilsen
Denis Nilsen is remembered for having killed several young boys and men by luring them to his house before killing them. He could sleep with the corpses on his bed for several days until the odor was too much to bear. He apparently did this to alleviate his loneliness. His actions would have been gone unnoticed had the neighbors not complained of blocked drainage. The plumber trying to unlock the pipes proposed for analysis of the pieces blocking the pipes and people were shocked at discovering that the pieces were of human fresh. He was later sentenced to life imprisonment in 1983 and has still remained to be remembered as one of the serial killers of the world.