With a plot described by the author and numerous critics as a modern adaptation of Romeo & Juliet, High School Musical is a story about two high school juniors from rival cliques – Troy Bolton (Zac Efron), captain of the basketball team, and Gabriella Montez (Vanessa Hudgens), a beautiful and shy transfer student who excels in math and science. Together, they try out for the lead parts in their high school musical, and as a result, divide the school. Despite other students' attempts to thwart their dreams, Troy and Gabriella resist peer pressure and rivalry, inspiring others along the way not to "stick to the status quo". Sharpay Evans (Ashley Tisdale), a drama queen and high school diva will do anything to sabotage the friendship between Troy and Gabriella and also get a lead in the school musical, assisted by her brother Ryan (Lucas Grabeel).
As described, each students of East High has different attitudes. As the succession of the movie goes broader, more and new casts were also introduced. Accompanied with Gabriella was her best friend, Taylor McKessie (Monique Coleman) and the captain of the school's Scholastic Decathlon team. Chad Danforth (Corbin Bleu) is Troy's bestfriend and also a member of Wildcats Team. Also includes Ryan Evans (Lucas Grebeel) and his sister Sharpay Evans (Ashley Tisdale), the two talented twins studied in East High. The other casts includes:
- Kelsi Nielsen (Olyesa Rulin) is the school's composer and pianist.
- Tiara Gold (Jemma McKenzie Brown) is another queen bee and Sharpay's apprentice.
- Jack Bolton (Bart Johnson) is Troy's father and the coach of the basketball team.
- Ms. Darbus (Alyson Reed) the stem drama teacher at East High.
- Zeke Baylor ( Chris Warren Jr.) friend's of Troy and Chad, also the member of the basketball team, also enjoys baking.
- Jason Cross (Ryne Sanborn) like Zeke, he was Troy and Chad's friend, the member of the basketball team. He also tends to ask silly questions.
