Sigmund Zeisler (1860–1931) was a German-Jewish U.S. attorney born in Austria and known for his defense of radicals in Chicago in the 1880s.

His wife was the famed concert pianist Fannie Bloomfield Zeisler.

Sigmund Zeisler was born in Bielitz, Austrian Silesia on April 11, 1860.

Zeisler graduated from the Northwestern University School of Law in 1884.

[3] After Fannie Bloomfield-Zeisler's death in 1927, Zeisler married Amelia Spellman in 1930.