A 27-year-old man sustained a serious head injury during the attack which happened at the top of Waverley Steps, Princes Street at around 10pm on Thursday 10th December 2015.
Detectives are keen to trace the man pictured who may be able to assist with enquiries.
Anyone who recognises the man in the images is asked to contact police immediately on 101, or alternatively the charity Crimestoppers anonymously on 0800 555 111.
Detective Constable Andy Cory from Gayfield CID said: “The man pictured is believed to be of significance to our investigation and anyone who can assist in tracing him is asked to come forward.
“Similarly we would ask the man to come forward himself and help with our investigation.”