“High School Musical” was the most watched TV movie of all-time when it was released back in ’06; the first film had a budget of over $4 million, showing the confidence Disney had in the success of the film. “High School Musical” marked the first major role for Zac Efron, who is now an A-list star: even though he never actually sang at all.
Efron’s vocal talents were still lacking at the time of the film’s shooting, especially as a result of going through puberty; this meant that he had to lip sync all of the words, so the songs you heard in the film were actually performed by Drew Seely. People didn’t seem to mind, and the movie became a huge hit. Although he did not sing in the first “High School Musical” entry, Efron did perform the vocals in the last 2 films of the smash-hit trilogy.