The first Academy Award (Oscar) for Best Documentary was awarded in 1942.
The first feature-length documentary film is generally considered to be Robert Flaherty's Nanook of the North, released in 1922. For a good overview of documentary film history, see the link below.
An Inconvenient Truth won the Oscar for Best Documentary of 2006.
Best Boy won the Oscar for Documentary - Feature - in 1979.
She was the subject of the 2008 Oscar winning Short Documentary.
The German actor, Emil Jannings was the first person ever to be awarded an Oscar for Best Actor in 1929.
Undefeated won the Oscar for Best Documentary in 2012. The documentary focused on a high school football team in Georgia and had not been considered the top contender for the prize.
The 2015 Best Documentary - Feature Oscar went to Citizenfour.
Taxi to the Dark Side (2007) won the Academy Award (Oscar) for Best Documentary Feature (Alex Gibney and Eva Orner).
An Inconvenient Truth.
Smile Pinki.
The first Oscar awarded for Best Actress was for 1927-28, and it went to Janet Gaynor for performances in three films: "Seventh Heaven," "Street Angel" and "Sunrise."
1940 - Hattie McDaniel was the first African-American win an Oscar. She was nominated for Best Supporting Actress, and she won for her role as Mammy in Gone with the Wind (1939).