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Seth Massey is a recurring antagonist in the 2017 Netflix Original series 13 Reasons Why, appearing as a minor antagonist in the first two seasons and a supporting antagonist in the third season. He is the abusive boyfriend of Justin Foley's mother and the main antagonist of his story arc.

He is portrayed by Matthew Alan.


Seth is first seen in Justin's apartment in season 1. Jessica, Justin's girlfriend, goes to the Foleys' apartment to look for Justin. Seth goes up to Jessica and rudely tells her that Justin's mother is worried sick about him.

He is later seen again with Justin's mother while putting his feet on the table. Justin angrily tells Seth to put his feet of the table, and Seth tells him not to "f***" with him.

In the penultimate episode of season 1, Seth becomes angry and annoyed with the cops stopping by his apartment and handing him subpoenas. He angrily blames Justin, and when Justin yells at him, Seth slams him onto the wall and starts choking him. Before he could strangle Justin to death, Justin's mother stops him, and Seth tells him to go live with that rich buddy of his. This drove Justin to run away from home and become homeless.

In season 2, Mr. Porter, the school guidance counselor, stops by the Foleys' apartment. Seth goes up to him, aggressively tells him that Justin stole money from him, and starts a fight with him. The police breaks the two up and takes them to the police station. They both end up getting released.

In the final episode, while everyone is at the Monet's coffee shop honoring Hannah, Seth angrily stares at Justin in his car while Justin is talking to Clay.

Later during season three, Seth's abuse of Justin becomes even worse as he continues harassing him for the money he owes. His attempts to murder him frighten to the point where Justin considers asking Bryce for help. Eventfully, Bryce does as he confronts Seth as the latter is pointing a gun at Justin. He relents after Bryce pays Justin's debt, but remarks that what Bryce did was "messed up" before leaving.

After Bryce's death, Seth is suspected of the murder by Clay, Justin and Ani because he sent Justin a text saying "you're next" on the night Bryce disappeared. They investigate Seth's den, where they find Bryce's watch, and when they are discovered Clay uses this to accuse Seth. However, Seth claims the watch was exchanged for drugs, and he intimidates Justin, causing Justin to push him. Seth pulls out his handgun, but Ani throws a bag at his arm before he can shoot, allowing the three to run away.

Later, Justin approaches Seth with an offer to deal drugs for him if Seth silences the dealer he was with on homecoming night. However, Seth is arrested and incarcerated shortly after for parole violations.



  • Amber Foley - Girlfriend


  • Justin Foley - Foster Son and Enemy; abused and tormented
  • Jessica Davis
  • Kevin Porter - Beat Up
  • Bryce Walker † - Bargainer
  • Clay Jensen
  • Ani Achola


Seth is a very violent and aggressive drug dealer. He is shown strangling Justin onscreen, and could have killed him if Justin's mother did not stop him. He also starts a fight with Mr. Porter that ended up with both of them getting dragged to the police station. That said, he does show signs of being more reasonable than he lets on as he gave Justin several chances to give him the money he owed. Furthermore, while he might have said it to get under Bryce's skin, he did remark that what Bryce did was messed up. Despite this, Seth's horrible treatment of Justin makes him one of the most heinous adults featured on the show.


           13-reasons-why-5888f5cfd8122 Villains

Baker's Dozen
Bryce Walker | Justin Foley | Zach Dempsey | Tyler Down | Marcus Cole | Courtney Crimsen

Montgomery de la Cruz | Coach Rick | Seth Massey | Mr. de la Cruz

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