| The JOCKS |
| TROY BOLTON - captain of the basketball team | |
| CHAD DANFORTH - number two on the basketball team, Troy’s best friend | |
| ZEKE BAYLOR - has a secret passion for baking | |
| Other Jocks | |
| The NERDS |
| JACK SCOTT - the PA announcer, (a.k.a.) the Velvet Fog of East High | |
| KELSI NEILSON - the mousey composer of Juliet and Romeo | |
| The THESPIANS |
| SHARPAY EVANS - president of the Drama Club | |
| RYAN EVANS - vice-president of the Drama Club | |
| James - an earthworm expressionist | |
| Susan - overwrought with emotion | |
| Cathy - a little too eager | |
| Alan - has a flair for couture | |
| Cyndra - has operatic aspirations | |
| Performance Art Kids | |
| The BRAINIACS |
| GABRIELLA MONTEZ - the shy new girl at school | |
| TAYLOR McKESSIE - president of the Science Club | |
| Martha Cox - has a secret passion for hip-hop | |
| Other Brainiacs | |
| The SKATER DUDES |
| Skaterdude - has a secret passion for the cello | |
| Skaterdude 2 | |
| Other Skater Dudes | |
| Other Students |
| Wildcat Cheerleaders | |
| Party Kids - guests in ski-lodge flashback | |
| Fans/Spectators - at the basketball championship game and the Science Decathlon | |
| The ADULTS |
| Karaoke M.C. - voiceover in ski-lodge flashback | |
| MS. DARBUS - drama teacher | |
| COACH BOLTON - basketball coach, Troy’s dad | |
| Ms. Tenny - voiceover chemistry teacher | |
| Moderator - voiceover science decathlon moderator | |