Gaja Alaga (3 July 1924 in Lemeš – 7 September 1988 in Zagreb) was a Croatian theoretical physicist who specialised in nuclear physics. He was born in noble family of Bunjevac Croats in the village of Lemeš (today called Svetozar Miletić) in northwestern Bačka in Kingdom of SHS (today in autonomous province Vojvodina, Serbia). He was the editor of the scientific magazine Fizika from 1978 until his death in 1988. He died in Zagreb in 1988. Today, a street in the Trnje city district of Zagreb bears his name.