Edmond O'Brien b. September 10, 1915. d. 1985 (Alzheimers)
Actor - Frank Bigelow in D.O.A.

Pat O'Brien b. November 11, 1899 d. October 15, 1983 (heart attack)
Actor - Knute Rockne, All American

Carroll O'Connor b. d. June 21, 2001 (heart attack)
Actor - Archie Bunker in All in the Family

Donald O'Connor b. 1925 d. Deptember 27, 2003 (heart failure)
Actor/dancer - Singin' in the Rain, There's No Business Like Show Business

b.Hugh O'Connor b. April 7, 1962. d. March 28, 1995 (suicide, shot himself in the head)
Actor - Lonnie Jamison on In the Heat of the Night - adopted son of Carroll O'Connor

Kenneth O'Donnell P. b. 1924. d. 1977
Press Secretery to JFK. After the assassination, he became a depressed alcoholic

Madalyn Murray O'Hair d? 1995 (missing presumed dead?)
Atheist activist - Disappeared with son Jon, grandaughter Robin and US$629,500 of American Atheists organization money

Georgia O'Keeffe b. 1887 d. 1986
Artist - American abstract painter

Merlin Olsen b. 1940 d. 2010 (mesothelioma)
Football great for LA Rams, Actor on Little House on the Prairie

Patrick O'Neal b.1927 d. 1994 (respiratory failure)
Actor

Tip O'Neill d. 1994 b. 1912
Speaker of the U.S. House

Heather O'Rourke b. December 27, 1975 d. February 1, 1988 (intestinal stenosis)
Actress - Poltergeist Girl

Maureen O'Sullivan b. May 17, 191. d. June 23, 1998 (heart attack)
Actress - Mia Farrow's Mother

Warren Oates b. 1928 d. 1982 (heart attack)
Actor

Merle Oberon b. 1911 d. 1979 (stroke)
Actress

Michaela Odone b. 1939 d. 2000 (lung cancer)
Real mother from story in the movie Lorenzo's Oil. Her son has outlived her.

Susan Oliver b.1937 d. 1990 (cancer)
Actress - Vina in the Star Trek pilot, The Cage

Lord Laurence Olivier b. 1907 d. 1989
Actor - former husband of Vivien Leigh

Johnny Olsen b. 1910 d. 1985 (brain hemhorrage)
Game show announcer - Price is Right, Match Game, Concentration

Aristotle Onassis b. 1906 d. 1975 (Myesthenia Gravis)
Greek tycoon - Husband of Jacqueline Kennedy Onassis

Christina Onassis b. 1950 d. 1988 (heart attack)
Heiress - Daughter of Aristotle

Jacqueline Kennedy Onassis b. 1929 d. 1994 (Non-Hodgkins lymphoma)
Former First Lady and later, editor at Doubleday

Robert J. Oppenheimer b. 1904 d. 1967
Nuclear Physicist

Jerry Orbach b. 1935 d. December 28, 2004 (prostate cancer)
Actor - Promises, Promises; Lennie Briscoe in Law and Order

Roy Orbison b. 1936 d. 1988 (heart attack)
Singer

Buck Owens b. 1929 d. March 26, 2006
Singer and host of Hee Haw

Jesse Owens b. 1913. d. 1980 (lung cancer)
Olympic Athlete