Clayton Jason Jensen is a fictional character created by author Jay Asher. He is the protagonist in Thirteen Reasons Why, a novel where a girl, Hannah Baker, dies by suicide. Clay is also the main character in the Netflix television series adaptation of Asher's story, 13 Reasons Why, where he is portrayed by Dylan Minnette.

Clay is the protagonist in the series and his major storylines have included his friendships with Hannah Baker and Tony Padilla. Other major storylines have included his reactions to the tapes and his deteriorating mental health, such as his struggle with anxiety and depression.

While the series has earned a divided and polarized reception from critics, readers and audiences praised it, and Minnette's performance was widely acclaimed.

In the Netflix series, Clay is an American high school student who is both a friend and brief love interest of Hannah, one of Clay's schoolmates. Both in the Netflix series and the book, Hannah's experiences prior to her death is told through Clay's eyes as he reacts to the content of Hannah's cassette tapes which she utilized to explain why she committed suicide. Although Hannah leaves explicit instructions before her suicide that Clay should listen to the tapes, she makes it clear that Clay is not one of her reasons for killing herself, but rather she wanted him to know exactly why she took her own life. At one point, in a vision of what Clay thought would happen if he told Mrs. Baker (Hannah's mother) about the tapes, he sees her strangling him with a cord.

In the second season, after the parents of Hannah Baker sue the school district for wrongful death, Clay and other students are asked to testify about what she went through. During their testimonies, Clay discovers things about Hannah that were not mentioned on the tapes, and questions what kind of person she really was. He also finds out that Hannah was not the only person who bad things happened to at the high school, and takes it upon himself to get to the root of the problem and stop it. Throughout this time, he constantly sees and has auditory hallucinations of Hannah speaking to him, as a manifestation of his guilt for not being able to help her while she was alive.

In the third season, Clay has, to a degree, recovered from his depression and violent tendencies, and along with the other people on the tapes, tries to help others do the same. However, after Bryce Walker, who raped Hannah before her death, is murdered, Clay becomes the prime suspect due to their history. Throughout the season, aided by his friends, Clay tries to find out who may have committed the murder, while those around him believe him to be guilty.

In the fourth season, Clay had interviews with the admissions officer from Brown and was accepted. His therapist (Gary Sinise) is introduced as a source of support for his depression and anxiety. He will go to Brown University after graduating from Liberty High School.

His mother is a lawyer who worked on the case on Evergreen County's side before withdrawing while his father is an English professor.