Zwan was an American alternative rock band that was formed by members of The Smashing Pumpkins, Slint, Tortoise, Chavez, and A Perfect Circle. Zwan was started in late 2001 by Billy Corgan, lead singer and guitarist of the Smashing Pumpkins, after the Pumpkins disbanded in December 2000. The band released only one album, entitled Mary Star of the Sea. The group disbanded acrimoniously after their 2003 world tour.