Recurring
Kerri Medders as Gwenny, Alexa's self-absorbed and manipulative rival on the girls' basketball team. Much to Alexa's dismay, Gwenny begins acting kinder towards her after learning about Alexa's illness. She also begins dating Lucas in season two, but they break up in season three.
Iman Benson as Reagan, a friend of Alexa and Katie. She is more sensible than Hannah. Often portrayed as self-centered, Reagan's selfishness is a running gag in the series.
Merit Leighton as Hannah, a friend of Alexa and Katie. She is more naive and dimwitted than Reagan. In season two, she joins the school's cheerleading team. Hannah has two mothers.
Nathaniel J. Potvin as Ryan, an awkward friend of Katie who worked with her in the school play. Ryan becomes Katie's first kiss, and although the two have feelings for one another, they are not acknowledged directly until the season two finale. He also has a single father.
Nadja Alaya as Megan, a friend of Alexa who also has cancer. Initially shown in the hospital, it is implied that Megan's sickness has begun to cease due to her attendance at Alexa's sweet sixteen.
Alyssa Jirrels as Vanessa (season 1), a student who worked in the school play. Because she lost the lead role to Katie, Vanessa is often passive aggressive towards her.
Ricky Garcia as Cameron (season 2), a dimwitted friend of Lucas and a member of his band. He often follows Lucas around, mirroring his style.
Scott Wordham as Barry, the manager at Wired, a local coffee shop in Wellard. He is often pessimistic and negative, but allows Katie to work as a barista.
Jordan Austin Smith as Cody (seasons 2–3), a new student whose locker is between Alexa and Katie's. Alexa befriends him, content with the realization that he is unaware of her cancer. He is also the school's mascot.
Constance Marie as Dr. Corts (season 3), Alexa's therapist. Katie is also treated by her for anxiety.
Gunner Burkhardt as Spencer (season 3), a boy Alexa meets at the hospital who has cancer (Hodgkin lymphoma). Although Alexa initially has no romantic feelings for him, Alexa later develops feelings for him and they start dating.
Barrett Carnahan as Aiden (season 3), a stress-free guy that works at Putt Putt Golf and acts as an annoyance for Katie. However, as time goes on, they develop feelings for each other. He later works as a barista at Wired.
Brady Smith as Joe Perry (season 3), a handyman that starts to date Jennifer.
