Karl Ernst Smidt (30 August 1903 – 11 January 1984[Note 1]) was a German naval commander who reached the rank of Konteradmiral with the West German Navy.

Smidt was born in Neuenhaus, district of Grafschaft Bentheim, in the Province of Hanover on 30 August 1903, the son of pastor Reinhard Petrus Wolbertus Smidt.

He began his naval career with the Reichsmarine on 31 March 1922 as a member "Crew 1922" (the incoming class of 1922) after graduation from the humanistische Gymnasium (humanities-oriented secondary school) in Hameln with his Abitur (diploma).

The marriage produced two daughters and a son, Antje, Hilke, and Wolbert Klaus, former First Director with the Federal Intelligence Service (Bundesnachrichtendienst).

Smidt joined the Confessing Church (Bekennende Kirche) with pastor Hermann Steen in Holthusen, district of Weener, after making an official visit to the Emsland concentration camp Esterwegen near Papenburg in 1935.