Megan Duskey was attempting to slide down a stair rail when she lost her balance and fell four storeys in Chicago’s Palmer House Hilton Hotel.
The 23-year-old was dressed as the Silk Spectre, a super-heroine from the comic book film Watchmen.
Miss Duskey’s family today paid tribute to her, describing her as someone who was ‘ready to make a difference.’
Police say alcohol did not appear to be a factor in the accident, which occurred at around 10.30pm on Saturday evening.
Miss Duskey had been at the hotel for around half-an-hour when she fell.
Close friend Elisa Pessetto, who was also at the sold-out Haunted Hotel Ball, said she had stepped away from the group for just a few minutes when the tragedy happened.
On her return, she found two of her friends collapsed and weeping on the stairwell floor.
‘I couldn’t even understand what they were saying,’ she told the Chicago Tribune.
‘Then someone said Megan fell.’
Ms Pessetto said a cousin of Miss Duskey’s was holding her body when firefighters arrived.
(The cousin) just said, “She’s gone.” She knew she was gone,’ Ms Pessetto said.
Hotel officials have refused to comment and police are investigating the death.
Miss Duskey’s parents are currently in Crete where they were today being comforted by friends and family.
Her father, James, would only say: ‘I’ve had an hour of sleep. What do you want to know? She was a beautiful girl.’
Miss Duskey was a teacher at Bright Elementary School where counsellors were on hand today to help children traumatised by news of her death.