Christmas has not been celebrated at the castle for 31 years
A bidder who won an auction to spend Christmas Day at Warwick Castle for up to 30 guests for £27,000 failed to pay up, the attraction said.
The castle was put up for private hire on the online auction site eBay last month. The experience had a reserve price of £25,000.
The money would have gone to a children's charity set up by the castle's owners Merlin Entertainment.
Bosses at the castle said they were "sorely disappointed".
Marketing director Georgina Kelly said the winning bidder "seemed to have gone to ground".
She said: "We are sorely disappointed as they may well have prevented a worthy charity from getting a significant contribution to help their work with disadvantaged, disabled and sick children."
It would have been the first time in 31 years that Christmas had been celebrated at the castle. Christmas Day is the only day of the year the attraction is shut to the public.
The Earl of Warwick sold the castle in 1978 to the Merlin Entertainment group.
The Christmas Day package, which was outlined on the online auction site, would have included a champagne breakfast in the library, followed by present opening around a 25ft (7.6m) tall Christmas tree in the Great Hall, all accompanied by live music.
The prize would have also included a private fireworks display in the courtyard and two nights luxury accommodation in a hotel nearby.