Heinrich Eugen Waentig (21 March 1870 – 22 December 1943) was a German economist and politician.

From 1909 to 1913, Waentig worked in Japan as an advisor to the Meiji government, lecturing in political economics and financial science at the Tokyo Imperial University.

He was elected to the Prussian Landtag in 1920 under the Social Democratic Party of Germany (SPD).

In 1927, he became Oberpräsident of the Province of Saxony and was appointed Prussian Minister of the Interior in 1930.

After resigning from the SPD in 1931 due to internal disagreements, he retired from politics.