The Swedish Academy, which awards the $1.4 million prize, honored Mueller, 56, for work that, "with the concentration of poetry and the frankness of prose, depicts the landscape of the dispossessed."
Before immigrating to Germany in 1987, Mueller received death threats in Romania after refusing to become an informant for its secret police when it was still a communist dictatorship.
Several of her novels that have been translated into English — including The Passport, The Land of Green Plums and Traveling on One Leg— explore life in a dictatorship and as a member of a minority.
Mueller's parents were members of the German-speaking minority in Romania. Her father served in the Waffen SS during World War II.
After the war, many German Romanians were deported to the Soviet Union in 1945, including her mother, who spent five years in a work camp in what is now Ukraine.
The last American to win the Nobel Prize in literature was Toni Morrison in 1993. Mueller is the 12th woman to win the prize in its 108 years.
