O

• Oberhauser, Josef
• Obrycki, Narcyz Tadeusz
• Ochshorn, Isaac Egon
• Office of Special Investigations
• Ohlendorf, Otto
• Ohrdruf
• Olère, David
• Open-Air Incinerations
• Operation Harvest Festival
• Operation Reinhardt
• Oranienburg
• order, to exterminate Jews
• OSI
• Ostrovsky, Leonid
• Ostrowski Company
• Oświęcim
• outdoor cremations