Oba Chandler

"Dave Posner / Dave Posno"

1989 - 1990

Obie D. Weathers

2000

Odell Barnes Jr.

1989

Olaf Däter

"The Granny Killer"

2001

Olan Randle Robison

1980

Oleg Murayenko

1998 - 2000

Oleg Naumov

1998

Oleg Petrovich Belov

2015

Oleg Protsenko

2000

Oleg Vladimirovich Kuznetsov

"The Balashikha Ripper / False Dmitry / Dmitry Fadeev"

1991 - 1992

Oleg Yurievich Chizhov

"The Birsky Maniac / The Birsky Monster / The Birsky Chikatilo"

2006 - 2007

Olga Hepnarová

1973

Olga Konstantinovna Strukova Briscorn

"The Kursk Saltychikha"

1818 - 1822

Oliver Newman

"Tiggy"

1931

Omaima Aree Nelson

1991

Omar Mir Seddique Mateen

2016

Omar S. Thornton

2010

Omer Ninham

1998

Ondrej Rigo

"The International killer / The Sock killer"

1990 - 1992

One L. Goh

2012

Orhan Aksoy

"The Parcel Killer"

2000 - 2001

Orlando Magaña Dorantes

2002

Orville Lynn Majors

"Angel of Death"

1993 - 1995

Oscar Franklin Smith

1989

Oscar Joseph Comery

1914

Oscar Leonard Carl Pistorius

"Blade Runner / The Fastest Man on No Legs / Tink Tink / Oz / Pistorius"

2013

Oscar Leschziner

"Slater"

1908

Oscar Ray Bolin

1986 - 1987

Óscar Segundo López Rodríguez

"The Monster of Lolol / El Monstruo de Lolol / El Hippie"

2012

Oswald Sibrol

1983 - 1984

Otis Tyrone McKane

2016

Otoya Yamaguchi

1960

Ottilie Klimek

"Tillie"

1914 - 1921

Ottis Elwood Toole

"The Jacksonville Cannibal"

1961 - 1983

Ottis Toole

"The Jacksonville Cannibal"

1961 - 1983

Otto Adolf Eichmann

"The Architect of the Holocaust / Ricardo Klement / Otto Eckmann / Adolf Bart / Otto Hening"

1939 - 1945

Otto Johann Anton Skorzeny

"Scarface of the SS"

1943 - 1945

Otto Stephen Wilson

1994

Ozan Selamet

2002

Özgür Dengiz

"Ankara Yamyamı (The Cannibal of Ankara)"

2007

Özkan Zengin

"The Well Driller Killer"

2008