Billie Joe Armstrong is an American musician who is the lead vocalist, guitarist, and primary songwriter of the rock band Green Day, which he co-founded with Mike Dirnt in 1987. He is also a guitarist and vocalist for the punk rock band Pinhead Gunpowder, and provides lead vocals for Green Day's side projects Foxboro Hot Tubs, the Network, the Longshot and the Coverups. Armstrong has been considered by critics as one of the greatest punk rock guitarists of all time.

Green Day is an American rock band formed in the East Bay of California in 1987 by lead vocalist and guitarist Billie Joe Armstrong and bassist and backing vocalist Mike Dirnt, with drummer Tré Cool joining in 1990. In 1994, their major-label debut Dookie, released through Reprise Records, became a breakout success and eventually shipped over 10 million copies in the U.S. Alongside fellow California punk bands Bad Religion, the Offspring, Rancid, NOFX, Pennywise and Social Distortion, Green Day is credited with popularizing mainstream interest in punk rock in the U.S.