| John C. Reilly | Larten Crepsley |
| Josh Hutcherson | Steve |
| Chris Massoglia | Darren Shan |
| Jessica Carlson | Rebecca |
| Michael Cerveris | Mr. Tiny |
| Ray Stevenson | Murlaugh |
| Patrick Fugit | Evra the Snake Boy |
| Daniel Newman | Pete |
| Morgan Saylor | Annie |
| Don McManus | Mr. Shan |
| Colleen Camp | Mrs. Shan |
| Ken Watanabe | Mr. Tall |
| Salma Hayek | Madame Truska |
| Orlando Jones | Alexander Ribs |
| Frankie Faison | Rhamus Twobellies |
| Willem Dafoe | Gavner Purl |
| Kristen Schaal | Gertha Teeth |
| Patrick Breen | Mr. Kersey |
| Tom Woodruff Jr. | Wolfman |
| Jane Krakowski | Corma Limbs |
| Drew Rin Varick | Loaf Head |
| John D. Crawford | Audience Member |
| Ritchie Montgomery | Pastor |
| Ted Manson | Policeman |
| Ann Mckenzie | Woman from Town |
| Monica Monica | Teacher |
| Adella Gauthier | Nurse |
| Beau Holden | Trucker |
| Patrick Fulton | Kid Passing By |
| Tyler Chetta | Kid in Hallway |
| Shaun Grant | Vampaneze |
| Trey Burvant | Singing Dad |
| Beth Burvant | Singing Mother |
| Evelyn Burvant | Singing Kid #1 |
| Anna Irene Dawson | Singing Kid #2 |
| Jonathan Nosan | Hans Hands |
| Madeline Gaudet | Shreiking Student |
| Erika Jensen | Rain Girl |
| Armal J. Perkins | Mr. Pipps |
| Troy Brenna | Vampanese |
| Ron Fagan | The Crying Man |
| Shawn Knowles | Mr. Kersey |
| Sam Medina | Madame Truska's Man |
| Natasha "Sasha" Angelety | Circus Freak (uncredited) |
| Michael Dean Baker | Mr. Piercing (uncredited) |
| Dewayne Bateman | Audience member (uncredited) |
| Blake Nelson Boyd | Mr. Afraid of the Ground Man. (uncredited) |
| Gino Galento | Madame Truska's man (uncredited) |
| Jewel Grosch | Student (uncredited) |
| Marc A. Hess | Cirque Camp Worker (uncredited) |
| Leah Kahn | Arcuaørius Firen (uncredited) |
| Cynthia LeBlanc | Funeral Mourner (uncredited) |
| Elton LeBlanc | Funeral Mourner (uncredited) |
| Brandon Molale | Vampaneze (uncredited) |
| Jake Moran | Snake boy's victim (uncredited) |
| Jay Oliver | The Adult Kid (uncredited) |
| Lyssa Prine | Audience member (uncredited) |
| Terry Lee Smith | University Administrator (uncredited) |
| Daniel Vincent | Theatre audience (uncredited) |
