In the Tennessee Williams play, The Glass Menagerie, there is difficulty in deciding who the protagonist is and who the antagonist is. Amanda, Tom, and Laura all have issues. Amanda cannot accept that her days of “gentlemen callers” are over, and she tries to live this again through forcing Laura to be more popular and social. Tom cannot live with the fear that he might be stuck in a dead end job forever when he really wants to be a writer. Laura cannot set aside her shyness, her health, and her feelings of insecurity to pursue any life of her own. If one had to pick, a protagonist it would probably be Laura. Her situation is partly self created, but much of her situation is controlled by and influenced by her mother and brother. Her biggest fault might be her weakness of character which does not empower her to move beyond her situation. Along those lines, Amanda must be considered the antagonist because every action belittles or weakens whatever actions Laura might take.
Enotes has a great study guide at the following link.