Karl Josef Seitz (German pronunciation: [kaʁl ˈzaɪts] ⓘ; 4 September 1869 – 3 February 1950) was an Austrian politician of the Social Democratic Workers' Party.

He, nonetheless, received adequate education and earned a scholarship so that he could enroll in a teacher-training college in the city of St. Pölten, Lower Austria.

On 21 October the Imperial Council members, representing the empire's ethnically-German provinces, moved to form a Provisional National Assembly for "German Austria".

He left office on 9 December but did not retire from politics and retained both his party chairmanship and his seat in the newly established National Council, Seitz now devoted his attention to Vienna local affairs.

[2] The extensive and competently administered public welfare and education programs that he implemented, particularly promoting the building of residences, were very popular, even by his party's opponents, and they were positively remembered for decades.

Even though a majority of Viennese considered his removal from office illegitimate, Seitz's political career had essentially been brought to an end.

Though now ill, Seitz served the newly established Social Democratic Party of Austria as its honorary chairman and a nominal National Council member until his death, at the age of 80.