There are several central themes in "A Streetcar Named Desire" by Tennessee Williams. These include:

Desire and Fantasy: The play explores the role of desire and fantasy in human behavior. Blanche, in particular, is obsessed with creating an illusion of her past and present life that is different from reality. Stanley, on the other hand, is driven by his desires and is determined to maintain his dominance in his relationships.

Illusion and Reality: The play also explores the tension between illusion and reality. Blanche lives in a world of illusion and refuses to face reality, while Stanley represents the brutal truth of reality. The play suggests that illusions can be dangerous and that facing reality can be painful but necessary.

Gender and Power: The play explores the power dynamics between men and women. Stanley uses his physical strength to assert his dominance over his wife and sister-in-law, while Blanche uses her sexuality to try to gain power over men.

Madness and Sanity: The play explores the boundaries between madness and sanity. Blanche's mental state deteriorates throughout the play, and it becomes unclear whether her madness is a result of her past traumas or a manifestation of her fragile state of mind.

Class Conflict: The play also explores the class conflict between the Southern aristocracy represented by Blanche and the working-class culture represented by Stanley. The clash between these two worlds is a major source of tension throughout the play.

Overall, "A Streetcar Named Desire" is a complex and powerful exploration of human behavior, relationships, and the struggle between illusion and reality.