Babbitt is the protagonist of the novel. He is more an anti-hero than a hero, since he is the victim of society and he never really wins his battle against its conventions. He tries, unsuccessfully, to break out of the confines of the traditional life he has chosen for himself.
The antagonist is less tangible, being more an attitude than a person. The conventions of predictable society are an antagonistic force. The weight of society's "normal" expectations bears down on Babbitt, making him feel stifled and conformed. At times, different people represent the conventions of modern American society. Many times, even Babbitt and his wife Myra embody this intangible antagonistic force. Other characters who symbolize this force are Stanley Graff, Virgil Gunch, and Chum Frink. Even the so-called rebels in society (Tanis and her bohemian "group") are basically members of a conformist group. In the end, it seems society is made of the forces of this antagonist. The irony in Babbitt is that the antagonist forces seem to win in the end. Babbitt is not the victor, but a resigned subject.
Babbitt strikes out against the conventional life he has built for himself, only to realize it is too late to change the course of his life. He finds himself seeking new challenges, embracing new ideas, rejecting every established aspect of his life. As a result of his actions, his reputation falters, his business begins to fail and his marriage suffers.
Babbitt's conventional life and his rebellious life intersect and the collision is so fierce he nearly loses everything - family, business, friends. His wife becomes seriously ill and he realizes he is going to lose everything if he does not accept his life as it is.
Babbitt resigns himself to the conventional life he chose long ago. Nothing has changed except his own willingness to accept his fate.