Billie Joe Armstrong (born February 17, 1972) is an American rock musician and occasional actor, best-known as the lead vocalist, main songwriter and lead guitarist for the American punk rock band Green Day. He is also a guitarist and vocalist for the punk rock band Pinhead Gunpowder and provides lead vocals for garage rock band Foxboro Hot Tubs when not working with Green Day.

Raised in Rodeo, California, Armstrong developed an interest in music at a young age, and recorded his first song at the age of five. He met Mike Dirnt while attending elementary school, and the two instantly bonded over their mutual interest in music, forming the band Sweet Children when the two were fifteen years old. The band changed its name to Green Day, and became one of the most successful rock groups of all time. Armstrong has also pursued musical projects outside of Green Day's work, including numerous collaborations with other musicians as well as serving as the primary vocalist for the bands Pinhead Gunpowder and Foxboro Hot Tubs.