Phoebe Heyerdahl is a fictional character in the animated series Hey Arnold!. She is Helga's best friend and sidekick, as Gerald is to Arnold. She was voiced by Anndi McAfee for the entire run of the series.
Phoebe is among the smartest children in the school (she was given a free pass to the 6th grade in "Phoebe Skips.") Her distinctive features include a huge lump of black hair at the top of her head bounded by a small yellow scrunchie, and stereotypes for smart children in animated shows, such as big eyeglasses (in Phoebe's case, with blue monochromatic lenses), a short stature, and squeaky voice.
Among her most notable moments was when she won the City Academic Bowl ("Phoebe Takes The Fall"), a competition that she should not even have been in, as Helga, in an attempt to win the only trophy her older sister Olga never won, had won her school's spot at the Bowl by forcing Phoebe to miss the final question (ironically, McAfee did not receive credit for the role in that episode). At the opposite end of the spectrum, she was utterly humiliated in front of the entire student body ("Phoebe's Little Problem") when she was caught passing gas into a microphone on stage as she was receiving an award, and subsequently refused to ever go to school again (somewhat ironically, the award was for her perfect attendance). Among her other achievements are winning the Parents Tournament Weekend with her parents ("Parents Day") and the City Go-Kart Grand Prix with Helga and Harold ("Grand Prix").
Not much is known about Phoebe's family, except that her father Kyo (George Takei) is of Japanese descent. In the Episode "Phoebe Cheats", her father said "Kampai!" (which approximately means "Cheers!" in Japanese) and is good at fencing, and her mother Reba (Jean Smart) has a strong Southern accent and is most likely from Kentucky (in "Phoebe Cheats", this is where Phoebe says she is from). Her parents only had speaking roles twice: "Phoebe Cheats" and "Phoebe's Little Problem".
Helga often makes Phoebe her own personal slave, as Phoebe is too nice to resist obeying her every whim. She is also one of the three people who know that Helga is in love with Arnold, the other ones being Lila and Dr. Bliss, Helga's psychiatrist.
Anndi McAfee and Francesca Marie Smith (the voice of Helga) also voice for best friends on another show, Recess, as two members of the Ashley clique. One of the creators of that show, Joe Ansolabehere, also wrote for Hey Arnold!.