Petro Havrylovych Dyachenko[a] (January 30, 1895 – April 23, 1965) was a military commander in different armies in Eastern Europe.

He joined the Ukrainian National Republic in its struggle against both White and Red Russian forces.

After the reorganization of the army on July 23, 1918, he took command of the Independent Zaporozhian Rifle Regiment (formed from his battalion).

On July 25 Dyachenko became member of the Ukrainian Central Committee [uk] (UCC) formed in Kraków on the Nazi Germany side.

In March 1944 he took part in organizing the 31st Schutzmannschafts Battalion (Ukrainian Legion in Kholm), which collaborated with Nazi Germany.

In 2015 Dyachenko was commemorated by Ukrainian Parliament with special state celebrations in his memory, raising protests in Poland.