Officers would like to speak to this man about an incident on Baldwin Street on Sunday 5 March at around 3am.
They believe he has information which could help their investigation.
He is described as white, between 5ft 10ins and 6ft 1ins tall, and thought to be aged 25-35 years old.
He has brown hair and a brown beard and moustache. He is shown wearing a white shirt, a black T-shirt, blue jeans and black trainers with white laces.
The investigation relates to an unprovoked attack outside Popworld, in which the victim was punched and kicked multiple times in the head. The offender then made off down Baldwin Street.
The victim attended hospital with a suspected broken nose. He has since been released from hospital to recover at home.
Officers would also like to speak to this man who they believe witnessed the offence take place.
He is described as white, also between 5ft 10ins and 6ft 1ins tall, with dark hair, a beard and a moustache. He is shown wearing glasses, a black t-shirt and a black shirt.
If you have any information about the incident, or can help us identify either men in the images, please call 101 and quote reference 5223052483.