William Francis Belzer (born November 5, 1968) is an American musician. He played bass guitar and drums while in high school, first attending Catholic Savior of the World High School Seminary in Kansas City, Kansas under the patronage of the diocese of Kansas City-Saint Joseph in Missouri, and then Rockhurst High School, in Kansas City, Missouri, from which he graduated in 1987.
While at Rockhurst High School he was the drummer for a band named Mongol Beach Party, a guitar-based jam-pop band. The band's breakup coincided with Belzer leaving to join Uncle Tupelo as drummer for a stint on their European-American Tour with Michelle Shocked, The Band and Taj Mahal in the early 1990s. When Belzer returned to Kansas City, he joined with Grumpy.
Belzer went on to other bands such as The New Amsterdams, Grant Hart and Cher UK, The Ssion. In December 2010 Belzer released his first solo release, "You Shouldn't Have." He currently plays with Lazy, The Sleazebeats, Ghosty and Mary Fortune.