| Gus |
Allen | Producer of Collateral Damage |
| John |
Cage | Composer and experimental musician |
| Ernesto |
Castorel | Mia's mentor, guest conductor at the philharmonic |
| Professor |
Christie | Mia's old music teacher |
| Lady |
Gaga | Famous singer |
| Mia |
Hall | Adam's ex-girlfriend |
| Vanessa |
LeGrande | Reporter |
| Mrs. |
Linden | Adam's former teacher |
| Les |
Paul Junior | Adam's guitar |
| Liz |
Phair | Adam's bandmate |
| Kim |
Schein | Mia's bestfriend |
| Mrs. |
Schein | Kim's mother |
| Bryn |
Shraeder | Adam's girlfriend, actress |
| Britney |
Spears | Pop singer |
| Beatrix |
Trixi | Henry and Willow's daughter |
| Brooke |
Vega | Punk rock diva, lead singer of Bikini |
| Dr. |
Weisbluth | Psychopharmacologist |
| Adam |
Wilde | Aka Wilde Man, narrator, musician |
| Aldous |
| Band manager |
| Bach |
| Composer |
| Cobain |
| Famous musician |
| Denny |
| Mia's father |
| Diane |
| Mia's aunt |
| Dylan |
| Adam's former bandmate |
| Fitzy |
| One of Adam's bandmates |
| Georgie |
| Stavros's son |
| Hendrix |
| Famous guitarist |
| Henry |
| Music friend of Mia's parents |
| Jonah |
| Adam's former friend |
| Joplin |
| Famous singer |
| Kat |
| Mia's mother |
| Mike |
| Adam's bandmate |
| Morrison |
| Musician |
| Nate |
| Adam's old friend |
| Rafaella |
| Italian model |
| Sarah |
| Liz's girlfriend |
| Stavros |
| Mia's old friend |
| Stim |
| Band producer |
| Teddy |
| Mia's brother |
| Viv |
| One of Adam's girls |
| Willow |
| Henry's wife |
