Quinn Coan, an American student at Cambridge University, was beaten because he looked like Harry Potter.
Coan was punched and had his head stamped on near the university early last month by a group of eight or nine young men.
Coan, on an exchange program from Occidental College in Los Angeles, was celebrating his 21st birthday at Pembroke College with friends.
When he was beaten, they were on their way to the city center, reported Cambridge News.
Right before the beating, the group began mocking the gown Coan was wearing, and made a remark about Harry Potter, Coan said.
“As we walked away I was punched on the right side of my head and then again and I fell to the ground,” he said. “My friends came to my side and then one of the group came over and just stamped on my head and broke my jaw. I had a black eye and a fractured jaw. It was terrible.”
Coan said that the attack was unprovoked and he believes it was because of the gown he was wearing.
Police have just released CCTV images of the attackers, and are asking the public to help identify them.
Anyone with information about the assault should contact DS Hine on 101 or Crimestoppers, anonymously, on 0800 555 111.