Gustav Ernesaks (12 December 1908 – 24 January 1993) was an Estonian composer and a choir conductor.
Ernesaks was born in Perila, Peningi Parish. He played an integral role in the Singing Revolution and was one of the father figures of the Estonian Song Festival tradition. One of his songs, set to Lydia Koidula's poem Mu isamaa on minu arm, became an unofficial national anthem during the years of Soviet occupation. He was also the composer of the Anthem of Estonian SSR used between 1945 and 1990.
Erneskas was married in 1935 to Stella Merjam. She preceded him in death in 1973. He died in Tallinn, aged 84. They had three sons: Ott Ernesaks, Jüri Ernesaks and Peep Ernesaks. A statue of him was erected in 2004 on the Tallinn Song Festival Grounds.