We can certainly argue that in his play The Glass Menagerie Tennessee Williams portrays Tom as the tragic hero.
A tragic hero reunites both debilitating and redeeming characteristics. He or she is often a regular person who has to overcome a series of obstacles, big obstacles, to finally come to a realization of the self. This realization will eventually become the causative factor for the character's imminent change. In other words, it is basically a character who has to go through a lot of bad stuff in order to achieve the good stuff.
We could classify just about every one of the four characters of the story as tragic, but only one of them decides to change the steps of the never-ending drama at home, and takes off. That is exactly what Tom does. He could not continue with a life leading nowhere, especially when he is expected to fulfill the needs of his mentally strange mother and his socially-crippled sister. His decision is tough: Leaving the women behind to fulfill his own dreams might seem selfish at a superficial level. However, that is the sacrifice Tom has to make in order to save himself from the imminent sinking of his dysfunctional family. This way it will not be all three lives lost to nothing.