Recurring
Jentel Hawkins as Angela Wells, Hazel's mother who is a therapist
Asante Jones as:
Marcus Wells, Hazel's father who is a parascience expert
Not Timmy Turner, a middle-aged man shown working various jobs throughout Dimmadelphia. His appearance is a homage to adult Timmy Turner from "The Big Problem!" and was confirmed to not be the actual Timmy by showrunner Lindsay Katai.
A.J. Beckles as Antony Wells, Hazel's older brother who left her for college
Iris Menas as Winn Harper, one of Hazel's friends who is non-binary, as is their voice actor
Merk Nguyen as Jasmine Tran, one of Hazel's friends
Marcus Montgomery as Whispers Fred, one of Hazel's classmates, who speaks quietly and makes ASMR videos
Kyle McCarley as:
Devin "Dev" Dimmadome, the son of Dale Dimmadome and grandson of legendary business tycoon Doug Dimmadome. He acts antagonistic toward Hazel until the episode "A New Dev-elopment", in which they become friends. At the end of the episode "Lost and Founder's Day", after their friendship is strained following his father's deceit, Dev receives a fairy godparent of his own, the now grown-up Poof (who now goes by Peri).
Jenkins, one of Hazel's classmates
JP Karliak as Dale Dimmadome, Dev's father and Doug's son. He was voiced by Dee Bradley Baker in the original series.
Carlos Alazraqui as:
Mr. Jorge Guzman, Hazel's teacher
Stuart and Hannibal, twin brothers who live in Hazel's apartment building
Denzel Crocker, a deranged former elementary school teacher and one of the archenemies of Hazel's predecessor, Timmy Turner. Crocker is still obsessed with fairies and is determined to prove their existence as well as to harness their power for his personal gain. Alazraqui reprises his role from the original series.
Grey DeLisle as:
Bev, one of Hazel's classmates and Dev's crush, who plays soccer and insists on calling it football
Mrs. Amy Krentz, Hazel's school principal
Mrs. Velasquez, one of Hazel's teachers
The Pe-Az, an intergalactic pea peace-negotiating team, wished by Hazel to get Dev to be kind
Vicky, a former babysitter and one of Timmy Turner's archenemies, who loves torturing children through hard labor. DeLisle reprises her role from the original series.
The Tooth Fairy, a fairy who handles tooth-related magic and Jorgen's wife. DeLisle reprises her role from the original series.
Eric Bauza as:
Trev, one of Hazel's classmates
Periwinkle "Peri" (formerly known as Poof), Dev's fairy godfather and the now grown-up son of Cosmo and Wanda. He was voiced by Tara Strong in the original series. Hairston stated that his name was changed from "Poof" to "Peri" because the former is a slur in many countries.
Elkniwirep "Irep" (formerly known as Foop), the Anti-Fairy counterpart of Peri and the now grown-up son of Anti-Cosmo and Anti-Wanda. Bauza reprises his role from the original series.
Dawnn Lewis as Tina Churner, Dimmadelphia's news reporter
Kyle A. Carrozza as The Pe-Az, an intergalactic pea peace-negotiating team, wished by Hazel to get Dev to be kind
