Which founding Beach Boy was Brian Wilson's high school classmate?

Al Jardine was the founding Beach Boy who was Brian Wilson's high school classmate.

Jardine and Wilson attended Hawthorne High School, where their friendship connected Jardine to Brian's younger brothers, Carl and Dennis, and to their cousin Mike Love. Jardine brought guitar playing and a background in folk music to the emerging group.

The five founders combined different roles: Brian developed the arrangements, Dennis played drums, Carl played lead guitar, Jardine played rhythm guitar, and Love was the main singer and occasional saxophonist. Their shared singing, rather than instrumental virtuosity alone, became the foundation of the Beach Boys' distinctive sound.

Jardine briefly left the group in early 1962 to attend dental school and was replaced on guitar by David Marks. That change sometimes causes Marks to be mistaken for a founder, but Jardine was part of the original five. He later returned and remained an important member of the band's classic lineup.