A 52-year-old man was taken to hospital with serious injuries after being attacked outside the Variety Bar at about 00:40 on 24 December.
The man in the image is in his early 20s with brown hair and was wearing a blue jacket, blue jeans and black and white trainers.
Police have appealed for information.
Police have released a CCTV image of a man they want to speak to in connection with a serious assault in Glasgow city centre on Christmas Eve.