Edwin W. Knappe (January 14, 1884 - ?) was an American machinist from Milwaukee who became a lawyer, and who served one term as a Socialist member of the Wisconsin State Assembly.
Knappe was born in Milwaukee on January 14, 1884; he attended Milwaukee's public schools, including one year at West Division High School. He left school at the age of 15 and became a journeyman machinist. In 1905, about the time he joined the Socialist Party, he left Milwaukee and worked his way around the world, spending several months in Australia, where he worked as a machinist. After returning to Milwaukee, he completed his secondary education in night school. He ran unsuccessfully for the Milwaukee County Board of Supervisors in 1908; served as deputy clerk of the circuit court from 1911 to 1913, and ran for the Assembly in 1912, losing to Republican alderman August Dietrich. Having spent three years in the Evening Law School of Marquette University, he passed his bar examination in 1913. He practiced law as a member of the firm of Kleist, Harriman & Knappe, and served as Milwaukee election commissioner from 1915 to 1918. He remained a member of the Machinists Union (Lodge #66) and served as attorney for District 10 of that union.
He was elected to the Assembly in 1918 to succeed fellow Socialist and lawyer Glenn P. Turner (who like Knappe was a member of Kleist, Harriman & Knappe) in representing the Tenth Milwaukee County Assembly District (the 21st and 25th Wards of the City of Milwaukee). He received 3,959 votes to 1,211 for Democrat Theo. Thielges; and was appointed to the standing committee on state affairs.