Police are hunting for a man dressed as Batman who attacked another man in a street knocking him unconscious.
The victim, was allegedly knocked to the ground by the Batman look-a-like outside the Chicago Rock Cafe in New Road, Oxford, early on Sunday morning.
A Thames Valley Police spokeswoman, said: "It was really a case of 'Kapow'! But this actually was a serious assault and we are very keen to trace this person."
The masked attacker then fled on foot, while the injured man was taken to the John Radcliffe Hospital in the city and later discharged.
"He was obviously very distinctive and someone will probably know who he was or will have thought: 'Oh yes, I was at that party'," the spokeswoman added.
The 'caped crusader' has been described as white, in full fancy-dress costume.
Police are appealing for witnesses to the assault or anyone who saw a man running down Hythe Bridge Street to contact them immediately.