Did you witness this assault? Or can you help us identify the man responsible?
Officers have released CCTV footage showing a brutal and unprovoked attack in Stoney Street, Nottingham.
The assault took place outside Bamboo Bar at 2.47am on 1 March 2015.
The victim was attempting to help a woman in distress when he was punched unconscious, suffering a fractured skull.
Det Insp Mike Allen said: “This was an unprovoked and cowardly attack. So often we see one punch assaults like this end in tragedy.
“In this case the victim had walked over to help a young woman and was instead punched to the floor suffering a serious injury.
“We would urge anyone who knows anything about this incident to call us on 101.”
If you can help please call Nottinghamshire Police on 101 quoting incident number 167 or Crimestoppers on 0800 555 111.