Aside from Clay, Alex is the student who is the most upset after receiving Hannah's tapes. He feels extremely guilty about the ways in which his actions made her life harder, and he appears to be struggling with depression. Alex has withdrawn from his friends, and he understands Clay's desire to bring Bryce to justice, but he also wants to admit his own culpability. He is the one character who consistently feels that they should all share the blame, and he faces major conflicts with the others as a result.
Ultimately, Alex's guilt becomes so intense that he shoots himself in the head. He is in critical condition at the end of the finale.