William B. Magnarelli (born March 20, 1949) is a member of the New York State Assembly, for the 129th district first elected in 1998. He is a Democrat. Magnarelli represents the 129th Assembly District, which includes the Northside, Westside, Eastwood and Valley areas of the City of Syracuse, as well as the towns of Geddes and Van Buren. In 1998, he won the election for an open seat.