Christopher, a former lecturer in Old and Middle English as well as Old Icelandic at the University of Oxford, is credited with drawing the 1954 map of Middle-earth for his father's novel The Lord of the Rings.

He also spent years compiling and editing the works of his father -- who died in 1973 -- before publishing many of them, including The Silmarillion in 1977 and The Fall of Gondolin in 2018.

"We have lost a titan and he will be sorely missed," Tolkien Society chairman Shaun Gunner said in a statement Thursday.

"Christopher's commitment to his father's works has seen dozens of publications released, and his own work as an academic in Oxford demonstrates his ability and skill as a scholar," Gunner added.

"Millions of people around the world will be forever grateful to Christopher for bringing us The Silmarillion, The Children of Hurin, The History of Middle-earth series and many others."

His death was confirmed by Daniel Klass, Christopher's brother-in-law, according to the New York Times. 

Read also: 'Tolkien' looks at early years of 'Lord of the Rings' writer

He died in Draguignan, southeastern France, local newspaper Var-Matin said.

Christopher was critical of the "commercialization" of his father's work in a 2012 interview with French newspaper Le Monde.

"Tolkien has become a monster, devoured by his own popularity and absorbed by the absurdity of our time," Christopher Tolkien was reported as saying.

"The chasm between the beauty and seriousness of the work and what it has become has overwhelmed me. The commercialization has reduced the aesthetic and philosophical impact of the creation to nothing.

"There is only one solution for me: to turn my head away."

Christopher was born in Leeds, Britain, on 21 November 1924. He joined the Royal Air Force during World War II and was stationed in South Africa.