Pēteris Slavens (Russian: Пётр Антонович Славен, romanized: Pyotr Antonovich Slaven; Cēsis, 5 April 1874 – Valmiera, 14 November 1919) was a Latvian Soviet military commander, who fought in the Russian Civil War.

After the October Revolution, he was forcibly re-activated by the Red Army in the summer of 1918, despite his poor health.

He commanded first a division, then from August the 5th Army in the East, and until January 1919 the Southern Front in the Russian Civil War.

Slavens received his demobilization for health reasons and then illegally crossed the border into independent Latvia.

The local authorities detained Slavens in November 1919 and put him in a POW camp, where he died in hospital from pneumonia.