The Beach Boys lineups

The Beach Boys began in 1961 when brothers Brian, Carl and Dennis Wilson formed a rock band with their cousin Mike Love and friend Al Jardine. Since then, the band has undergone many variations in composition, with representation by fill-ins onstage as often as not as original personnel pursued other careers, hired, or rehired, took extended breaks for medical reasons, or died.

Wilson neighbor David Marks appeared on their first four albums, played with the group in its formative stages, and was a member from 1962 to 1963 as a replacement for Jardine, who had left the group to attend college. Jardine returned to the band in 1963 as an onstage fill-in for Brian, who was already feeling the stresses of touring. Marks rejoined the band in 1997, during Carl's last illness, and remained with them for two years.

In 1965, Bruce Johnston became a member and also filled in on bass and sang some of Brian's parts live. In 1972, drummer Ricky Fataar and guitarist/bassist Blondie Chaplin joined the band, while Johnston had officially resigned from the group. In 1973 and 1974 Fataar and Chaplin left. In 1979, Johnston returned.

Founding members are bolded. Only Love and Johnston currently tour as "the Beach Boys";

Though not official members of The Beach Boys, sidemen have helped them during recording sessions and live performances over the years.

Keyboard players Daryl Dragon and Toni Tennille (later the "pop" duo The Captain & Tennille), have toured with the band.

In 1969, drummer Mike Kowalski and bassist/guitarist Ed Carter became two of the first outside musicians to join the group. Percussionist/drummer Bobby Figueroa was added in the mid-1970s and played through 1987. Billy Hinsche (of Dino, Desi, & Billy fame) was a longtime member of the supporting band throughout the 1970s, '80s and '90s. Carli Muñoz, who been playing keyboards with the band since 1970, replaced Daryl Dragon on keyboards from 1971 until 1979, when Mike Meros took over from May 1, 1979 until July 4, 2000.

...
Wikipedia