Sergey Viktorovich Efremov (5 August 1973-2 February 2025) was the deputy governor of Primorsky Krai from 28 February 2024 to 2 February 2025. He headed the regional branch of DOSAAF and served as vice mayor of Ussuriysk before becoming a colonel in the 155th Guards Naval Infantry Brigade during the Russo-Ukrainian War. He was appointed deputy governor of Primorsky Krai in 2024, only to be killed by a landmine in Kursk Oblast in 2025, making him the highest-ranking Russian casualty of the war.