Alexander Martin Barr is an American musician. He is best known for his time as the lead singer of the Dropkick Murphys, whom he joined in 1998. As of 2022, he is on hiatus from the band to care for his mother. He was also a founder and lead singer for The Bruisers, which he helped form in 1988 in Portsmouth, New Hampshire. His first band, circa 1984, was called D.V.A.. He also went on to front 5 Balls of Power with future members of Scissorfight, The Radicts, L.E.S. Stitches, and US Bombs, before he formed The Bruisers.