Yelena Konstantinovna Ubiyvovk (Russian: Елена Константиновна Убийвовк; 22 November 1918 – 26 May 1942) was a partisan and leader of a Komsomol cell during the Second World War.

[2] In November 1941 Ubiyvovk founded a Komsomol underground resistance cell that came to be nicknamed "The Undefeated Poltav Women".

In the group's six months of existence they spread 2,000 anti-Axis leaflets, helped 18 Soviet prisoners-of-war escape, stole weapons from German depots, burned down an office holding records and lists of people scheduled to be exiled into forced labor, and helped other cities establish resistance movements.

The operative was tortured and eventually betrayed the group members, identifying Ubiyvovk and Sapigo as individuals of interest.

Ubiyvovk had been tortured and interrogated twenty-six times before her execution and had sent letters requesting poison so she could kill herself if needed.