7. John Wayne Gacy (33 victims)
John Wayne “Pogo” Gacy or the “Killer Clown” was a serial killer who murdered 33 boys between 1972 and 1978. He buried 26 of his victims in the basement, 3 elsewhere in his house and thrown 4 others into a nearby river. Gacy actively participated in various children parties and parades; and he was commonly known by locals as “Pogo, The Clown”. Gacy was sentenced with death penalty and after his death was confirmed, Gacy’s brain was removed by researchers to isolate abnormalities that caused his violent behavior.