Andy Serkis will give a continuous, live reading of The Hobbit – lasting around 12 hours.
The star, 56, best known as Gollum in The Lord Of The Rings and Hobbit films, will read the entire book from start to finish with no breaks.
Money raised from the performance will be split equally between NHS Charities Together and Best Beginnings.
Serkis said: “So many of us are struggling in isolation during the lockdown.
“While times are tough, I want to take you on one of the greatest fantasy adventures ever written, a 12-hour armchair marathon across Middle Earth whilst raising money for two amazing charities which are doing extraordinary work right now to help those most in need.”
Serkis is calling on fans who watch his reading of JRR Tolkien’s 1937 novel to donate via the GoFundMe campaign.
The reading, starting at 10am on Friday, is estimated to take between 10 to 12 hours.
Serkis has been an ambassador of Best Beginnings, which works to support babies, toddlers, pregnant families and new parents and aims to reduce inequality, for over six years.
NHS Charities Together is the umbrella organisation bringing together all the official charities of the health service.
Donations can be made at https://www.gofundme.com/thehobbitathoncovid19appeal.
The livestream will start at 10am on Friday with the link posted on the GoFundMe page on Friday morning.