Karl Matthew Alvarez is an American bassist and songwriter for both the Descendents and All, the band that resulted after the Descendents disbanded again in 1987. Alvarez joined the Descendents after the Enjoy! album from his previous bands The Massacre Guys and Bad Yodelers, and played on all of the All albums, and the Descendents albums All, Everything Sucks, Cool To Be You and Hypercaffium Spazzinate. Unlike previous Descendents bassists Tony Lombardo and Doug Carrion, who both used a pick, Alvarez plays finger style bass, and he also provides backing vocals when live. Since joining the band he has been a major songwriter contributing many songs to All, Everything Sucks and Cool To Be You. In the summer of 2006 he joined Gypsy Punk band Gogol Bordello for part of the Van's Warped Tour and the Reading and Leeds Festivals. Alvarez currently plays guitar and sings in Endless Monster and the Vultures.