Karol Michał Popiel (28 October 1887 – 6 June 1977) was a Polish politician of the christian democracy tendency and writer.

In the period from September to December 1930, he was imprisoned by the Sanation authorities in the Brest Fortress for political reasons.

After German aggression against Poland, he went to France and later to United Kingdom, where he worked in the structures of the Polish government-in-exile.

In exile, he sought recognition by Western European countries of the Poland-German border on the Oder and Lusatian Neisse.

Publications issued in exile in Polish People's Republic due to censorship were not published until the 1980s.