Michael Ryan Pritchard (born May 4, 1972), known professionally as Mike Dirnt, is an American musician, songwriter, and singer. He is best known as the co-founder, bassist, backing and occasional lead vocalist of Green Day. He has also played in several other bands, including The Frustrators. His stage name was originally a nickname that his friends from grade school gave him, as he constantly played "air bass" and made a "dirnt, dirnt, dirnt" noise while pretending to pluck the strings.
He is also known as Michael Ryan Pritchard.