Alan Charles Jardine (born September 3, 1942) is an American musician, singer, and songwriter who co-founded the Beach Boys. He is best known as the band's rhythm guitarist, harmony vocalist, and occasional lead singer on singles such as "Help Me, Rhonda" (1965) and "Then I Kissed Her" (1965).

Jardine originally performed in a folk group while a student at Hawthorne High School, where he befriended Brian Wilson. After both enrolled at El Camino College, Jardine invited Wilson to record at a professional studio and together formed the Beach Boys with Brian's brothers Carl and Dennis and their cousin Mike Love. Jardine left the group in early 1962 and returned in late 1963. From the late 1960s to 1970s, he contributed as a co-writer or co-producer on singles such as the originals "California Saga/California" (1973) and "Lady Lynda" (1979, a UK top-10 hit), and cover versions of "Cottonfields" (1970) and "Come Go with Me" (1979).

Jardine was inducted into the Rock and Roll Hall of Fame as a member of the Beach Boys in 1988. Following Carl's death in 1998, he stopped touring with the band and has since performed as a solo artist. He has released one solo studio album, A Postcard from California (2010), and EP, Islands in the Sun (2025). In 2011, he briefly rejoined the band for their 50th anniversary tour and subsequently toured alongside Brian until 2022. Since 2025, Jardine has performed with the Pet Sounds Band, a reformed version of Wilson's supporting band.