It occurred just after 3am on Friday 26 April 2013, outside the McDonalds fast food restaurant on Blake Street, as the offender, a woman dressed as the Incredible Hulk, left the restaurant with a group of other people.
As a result of the assault the victim, a 17-year-old local girl, was left with bruising to her face and a black eye.
At the time of the incident the woman suspected of the assault was covered in green body paint with dyed red hair. However, she is believed to be a white woman, in her late teens or early twenties and around 5ft 8in tall with a medium build.
PC Cheryl Hunter, of York Safer Neighbourhood Team, said:
This appears to have been a wholly unprovoked assault. Thankfully the injuries were not too severe. However, the outcome could have been far more serious.
If you witnessed the assault or can identify the woman I need to speak to about this incident, I ask that you contact the police or Crimestoppers straight away.
Anyone who can help the police with their enquiries is asked to contact York CID on 101, press option 2 and ask for Cheryl Hunter. Alternatively information can be emailed to firstname.lastname@example.org
Or call Crimestoppers anonymously on 0800 555 111 quoting reference number 12130066826.