Leslie Howard
(3 April 3rd 1893, London, England - 1 June, 1943, Bay of Biscay)

When the war broke out in Europe, Leslie Howard didn't stay in the United States for events which accompanied the world premiere of GWTW. He went back to England and got involved with the war effort. He made more films (Pimpernel Smith - 1941) and did radio broadcasts. He allegedly had connections with the British intelligence. In 1943 he undertook a month-long lecture tour of Spain and Portugal. 
He died on June 1st, 1943 when the commercial airliner he was flying from Portugal was shot down by the Germans, over the Bay of Biscay. The so-called mistaken identity theory suggests that the Germans thought Winston Churchill was abroad this plane. 

He was survived by his wife Ruth Martin, and his children: Ronald and Leslie Ruth. 

Victor Fleming
(February, 23rd, 1883, Pasadena, CA - 6 January, 1949, Cottonwood, AZ)

After GWTW, Victor Fleming directed Dr. Jekyll and Mr. Hyde (1941), Tortilla Flat (1942), A Guy Named Joe (1943), Adventure (1946) and Joan of Arc (1948).
He died in 1949 of a heart attack. Even though he made so many memorable movies (such as The Wizard of Oz, Red Dust, Test Pilot), he remains relatively unknown to the general public, but some of his famous fans include: Steven Spielberg (remade A Guy Named Joe, as Always) , James Cameron and Philip Kaufman. 

Thomas Mitchell
(11 July, 1892, Elizabeth, NJ - 17 December, 1962, Beverly Hills)

Even though year 1939 was the best in his acting career (Gone With the Wind, Mr. Smith Goes to Washington, Oscar for The Stagecoach) he went on to make dozen of other movies in the following decades. The most famous included: It's a Wonderful Life (1946) and High Noon (1952). His considered one of silver screen's best character actors. He also worked for television, and in 1960 originated a role of Lieutentant Colombo.
He died in 1962 of cancer. 

Barbara O'Neil
(17 July, 1910, St. Louis, MO - 3 September, 1980, Cos Cob, CT) 

The year following GWTW, Barbara O'Neil received an Oscar nomination for her role in All This and Heaven Too. She continued making movies until 1959, but she preferred working on Broadway. Meanwhile she divorced her husband, Joshua Logan, a famous Broadway producer. She retired in 1960 after appearing in Little Moon of Alban on Broadway. She died in 1980. 

Hattie McDaniel
(10 June, 1895, Witchita, KS - 26 October, 1952, Woodland Hills, CA)

Evelyn Keyes
Ann Rutherford
Ona Munson
Rand Brooks
Butterfly McQueen