William C. Zumach (October 16, 1887 – July 1981) was an American laborer, engineer, union organizer, and Socialist politician from Milwaukee, Wisconsin.

[2] Zumach was a strong advocate of cooperation between the Socialist and the Non-Partisan League, but was distressed by the failure of NPL congressmen to support Victor Berger when he was refused his seat in the House.

[3] Zumach was elected to the Senate for the 6th District (6th, 7th, 9th and 10th wards of the City of Milwaukee) in 1916 to succeed Democrat George Weissleder (who was not a candidate for re-election), receiving 4,147 votes to 4,006 for Republican Charles Meising, 1,744 for Democrat Charles Jungmann, and 73 for Prohibitionist Henry W. Schmidt.

[4] He did not run for re-election in 1920, but was succeeded by fellow Socialist Joseph Joshua Hirsch, who ran unopposed.

[5] As of April 1934, Zumach was announced as a speaker at the annual May Day celebration of the Socialist Party of Waukegan and North Chicago, Illinois.