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| Name | Life | Profession | Cause of death | Reference |
|---|---|---|---|---|
| Hugh O'Connor | 1962–1995 | Actor | Suicide under influence of cocaine. | |
| Lani O'Grady | 1954–2001 | Actress | Multiple drug intoxication. Vicodin and Prozac were found in her bloodstream | |
| Johnny O'Keefe | 1935–1978 | Singer | Conflicting sources indicate drug overdose, or simply heart attack. | |
| Pascale Ogier | 1958–1984 | Actress | Unspecified drug overdose. | |
| Alice Ormsby-Gore | 1952–1995 | Socialite | Heroin overdose. | |
| John Patrick Oswald aka Jani Lane | 1964–2011 | Singer-songwriter (Warrant) | Alcohol poisoning. | |
| Bryan Ottoson | 1978–2005 | Musician (American Head Charge) | Prescription-drug overdose. Accidental. |
Read more about this topic: List Of Drug-related Deaths