Brainbox is a Dutch rock group from the late 1960s/early 1970s. The band was founded in Amsterdam by guitarist Jan Akkerman , drummer Pierre van der Linden and singer Kazimir Lux (Kaz). Their debut single was "Down Man", which established their progressive blues sound. They had several hit singles in the Netherlands, including "Between Alpha and Omega", "Doomsday Train", Reason to Believe and "Smile". Soon after they released their first album, Jan Akkerman and Pierre van der Linden left the group to join Focus.

After Pierre van der linden and Jan Akkerman left, Brainbox bass player Cyril Havermans also followed to join Focus, replacing the original bass player Bert Ruiter. They were replaced by guitarists Herman Meyer and Rudie de Queljoe and drummer Frans Smit. Meyer was later replaced by John Schuursma. After Kaz Lux left the group in 1971, their popularity waned and they split up in 1972. In 2004 Kaz Lux reassembled the band (though without Jan Akkerman) and they performed in the Netherlands. In 2010 and 2011 the band performed again and recorded a new studio album The 3rd Flood.