Lewis's books have been adapted multiple times for the screen, including several TV series and, most recently, three films created by Disney from 2005 to 2010.
But the series isn't without its controversies, and Lewis's novels have been criticised in the past for things like its religious subtext and apparent sexism.
Here is everything that you need to know about the books and why they are seen as controversial to some.
The Chronicles of Narnia controversies explained
Lewis wrote The Chronicles of Narnia between 1950 and 1956, and the series consists of seven books which were published as follows: The Lion the Witch and the Wardrobe, Prince Caspian, The Voyage of the Dawn Treader, The Silver Chair, The Horse and his Boy, The Magician's Nephew and The Last Battle.
Though it wasn't published first, The Magician's Nephew is a prequel to the series as is The Horse and his Boy, and their storylines are not connected to the main storyline regarding the Pevensie siblings Peter, Susan, Edmund and Lucy – who are transported from war-torn Britain to Narnia.
Lewis was first converted to Christianity by Lord of the Rings author JRR Tolkien, his longtime friend and later rival (more on that later), and it proved integral to his future as a writer.
The author wrote Narnia as a Christian allegory, for example the lion Aslan is seen as a representation of Jesus, while the Pevensie siblings are referred to as sons of Adam and daughters of Eve in the books. The Magician's Nephew also reads as a recreation of the biblical story of Adam and Eve.
When Lewis was making The Chronicles of Narnia he was praised for his ability to weave in Christian writing into the children's books, particularly because at the time Lewis was a lecturer in Christian topics at Oxford University and also wrote on the subject in his work The Screwtape Letters.
Lewis and Tolkien were close during their early years as authors, but Tolkien is known to have not liked The Chronicles of Narnia because of how overt it was in drawing on Christian imagery.
Lewis's use of Christian imagery has since drawn criticism to the series, for example His Dark Materials author (and known atheist) Phillip Pullman disparaged the novels as "propaganda" in 2002.
At a book event, per the Guardian, Pullman said he'd read Lewis's work as a teacher and "realised that what he was up to was propaganda in the cause of the religion he believed in".
On the other end of the spectrum, in 2010 Liam Neeson, who voiced Aslan in the Disney films, drew some criticism for saying the lion is not meant to only represent Jesus.
Per Reuters, he said in a press conference: "Aslan symbolises a Christlike figure, but he also symbolises for me Mohammed, Buddha and all the great spiritual leaders and prophets over the centuries."
This led to backlash from those in the Christian community, who feel Lewis's religious views are integral to understanding the meaning behind the books.
JRR Tolkien and CS Lewis
Tolkien and Lewis, as mentioned, grew very close when they first met, bonding over their experiences in the First World War, their respective childhoods, and their love of writing.
During the early years of their friendship the pair enjoyed each other's company so much that they even created a group of like-minded authors known as The Inklings.
When Lewis read a draft of The Lion, The Witch and The Wardrobe to The Inklings it was said that Tolkien was "horrified" by what he'd read, because he hated the way Lewis had taken different aspects of various mythologies and biblical tales and repurposed it for his story.
Alan Jacobs, a literature professor who wrote a book about Lewis, explained that the inclusion of Father Christmas in Narnia "set [Tolkien's] teeth on edge", for example.
For years they encouraged each other's works, but tensions began to rise between the pair over things like the speed with which Lewis wrote and his rise in popularity, which led to the authors becoming rivals.
This resentment and rivalry eventually led to an estrangement between the pair until a few weeks prior to Lewis's death in 1963.
Racism and sexism
Lewis's work has also been criticised for being sexist and racist in the past, with Monika Hilder writing in her work The Feminine Ethos in CS Lewis' Chronicles of Narnia that the author could be seen as a "misogynist".
The Chronicles of Narnia sees its characters follow very strict gender roles: Susan is shown to be motherly, while Peter is depicted as a natural-born leader and later gifted a sword by Father Christmas. Susan's depiction in later books has also been deemed sexist.
JK Rowling called out the fact that Susan is unable to return to Narnia in The Last Battle, with The Harry Potter author commenting in an interview with Time: “There comes a point where Susan, who was the older girl, is lost to Narnia because she becomes interested in lipstick.
"She’s become irreligious basically because she found sex. I have a big problem with that.”
Evil is also personified in the books as distinctly feminine, though not exclusively. This is most memorably shown through the White Witch (played by Tilda Swinton in the Disney films) who poses a threat to Aslan and the Pevensie children in The Lion, The Witch and the Wardrobe.
Depictions of the Calormene Empire in The Horse and his Boy has been called racist. Pullman has previously criticised the books for both this and its apparent sexism, saying: "It is monumentally disparaging of girls and women. It is blatantly racist. One girl was sent to hell because she was getting interested in clothes and boys."
He has also said of the books: "I find them very dodgy and unpleasant – dodgy in the dishonest rhetoric way – and unpleasant because they seem to embody a world view that takes for granted things like racism, misogyny and a profound cultural conservatism that is utterly unexamined."
The Chronicles of Narnia: The Lion, The Witch and the Wardrobe is streaming on Disney+.