Who is the main character in The Glass Menagerie, is he/she also the protagonist, and is there an antagonist?

Tom Wingfield is the protagonist or main character in the play, he is also the narrator.

"The protagonist of a literary work is the main character, who must change in some way during the course of the events, even if the change is entirely internal. Tom is clearly the protagonist of The Glass Menagerie. Although he is not heroic and will probably never triumph over his obstacles, he does take action by the end of the play."

Amanda Wingfield, Tom's mother is the closest thing to an antagonist in the play, she is the clearest villain in Tom's life. She presents him with the greatest conflict, blocking him from having a life of choice and freedom.  He must overcome her constant, demanding and nagging behavior to escape from the confining apartment. 

Tom must contend with the guilt of leaving his sister Laura behind, in the same way that Mr. Wingfield, his father abandoned the family so many years ago.  Tom struggles with the dismal life that he shares with his mother and sister, but her criticism of his every move eventually becomes too much for him to bear. 

In the end of the play, Tom must escape to survive, even though he tells the reader that he is haunted by the spectre of his sister, Laura, who he left behind.