Which author is famous for his existentialist themes in works such as "No Exit"?

The choice of Jean-Paul Sartre as the correct answer is based on his prominent role in existential philosophy and literature. Sartre's play "No Exit" is a quintessential example of existentialist themes, exploring concepts such as freedom, identity, and the nature of existence. Through dialogue and character interactions, Sartre presents the idea that "hell is other people," which encapsulates his existentialist views on relationships and self-perception.

In contrast, while the other authors listed have made significant contributions to literature, their works are not primarily defined by existentialist themes. Lorraine Hansberry is known for her social realism and exploration of race and identity in plays like "A Raisin in the Sun." Henrik Ibsen's works often examine societal norms and individual morality, but he is not specifically categorized under existentialism. Arthur Miller focuses on the American experience and moral dilemmas, particularly in plays like "Death of a Salesman," but does not engage with existentialist philosophy as directly as Sartre does. Thus, Sartre is the clear figure associated with existentialist literature.