Kazimierz Badowski (15 August 1907, Regów Stary – 6 July 1990) was a Polish Communist activist.

Working as a docker in Gdańsk, he rose through the ranks of the trade union movement to become a figure in the Communist Party of Poland. In 1925, he left the party in the face of what he saw as an increasingly Stalinist ideological outlook. He became a Trotskyist, founding the International Revolutionary Current, an informal network of various anti-Stalinist, Trotskyist and other Marxist organisations. He was able to survive all of the Nazi concentration camps only to be imprisoned by Stalin in the early 1950s and again from 1962 to 1964.

He promoted the Esperanto language as part of the Trotskyist movement.

He died in 1990, living his later years paralysed and unable to communicate.

• Hass, Ludwik (Winter 1995–1996). Richardson, Al (ed.). "Against All Odds - True to the Ideals of his Youth". Revolutionary History. 6 (1). ISSN 0953-2382.