The chronicles of Narnia and the Lord of the Rings were written by CS Lewis and JRR Tolkein respectively. Both were close friends; part of a clique of writers at Oxford in the 40s and 50s called the Inklings that hung out together; and they critiqued and edited each other's series before they were published. So it makes sense that there were many crossover themes and similar characters between the novels. The prophecies of the Pevensies becoming kings and queens is like the prophecy of Aragorn returning and becoming king. Aslan sacrificing himself to the White Witch and then getting resurrected is like Gandolf sacrificing himself in the battle with Balrog and then resurrecting himself. Gandolf the Grey, and the White Wizard are monikers like the White Witch; or The Emerald Witch. Both series draw heavily on mythology: fauns, gollems, centaurs, elves and wraiths are all figures from Greek and Norse mythology. Balrog is a derivation of Magog, a mythological figure. Fenris Ulf is also a famous gargantuan wolf from Hell in Norse mythology, and he turns up in Narnia. JRR Tolkein's concept of the mystical rings of the Gods, used to form the universe are directly lifted from Norse mythology, from Wagner's Ring Cycle and from the Volsung Saga; so is his epic battle of mankind to pursue ancient cursed objects. And CS Lewis' 100 years of winter followed by the prophecized battle to end all battles is also taken from Norse mythology and the concept of Ragnarok and Armeggeddon. Edmund betraying his family and turning to the dark side, only to redeem himself at the end by sacrificing himself to destroy Jadis' magic want is similar to Borimir's confrontation of Frodo, and then him sacrificing himself to the Orcs to save them. Both Jadis and Sauron are symbols of the Devil. Taj and Saruman are symbols of the Devil as well. Aslan is a symbol of Christ; and the Emporer Beyond the Sea is God himself. Gandolf, the Elves, and Galidriel all seem to be to varying degrees Christ figures; and the Angels of Heaven as well. Manwe is God in the Tolkein universe. Just as Lewis had his Emporer beyond the Sea, Valinor is also translated as "one beyond the sea". Valinor is heaven in Tolkein's universe; it's also a loose copy of Norse mythology's Valhalla; their Heaven; their hallway of the Gods. The Valar in Tolkein are the Angels in his series. Narnia touches on magic rings in the Magician's Nephew, which is clearly borrowed from Tolkein, but also ultimately Norse mythology; which originated the idea of mystical rings used by the Gods to create the universe and then used by man for various purposes. Narnia also describes many different intersecting fantasy worlds in Magician's Nephew which again is Norse mythology concept; with it's Nifleheim and Muspleheim and Valhalla; and it's 9 worlds of the Gods. Norse mythology conceptualizes 9 intersecting netherworld, with the world of man at it's center; or Midgard, sometimes called Middle Earth; and this is absolutely where Tolkein got that concept. Middle Earth has the last ships to Valinor, the great Ships to the Netherworld; which is again borrowed from Norse mythology and Viking traditions a building a burning funeral pyre for Kings on and setting it out to sea on a ship. Famous mythological creatures and famous characters from folklore make cameos in each. The Gollem appears in Lord of the Rings, and St. Nicholas appears in Chronicles of Narnia, as well as Fenris Ulf and Lillith Queen of the Demons. Tom Bombadil is a cameo from Tolkein's earlier book; The Red Book, "Tales of Tom Bombadil". "Adam and Eve" are used as universal monikers for people in the Lion the Witch and the Wardrobe. "Gimli" the dwarf is reference to Gimle, a world of Norse mythology. And "Grima" is an old English word for "mask". Both series are linked to man: in Lord of the Rings JRR Tolkien describes how the Hobbits are becoming taller and taller; becoming men essentially; hinting that Middle-Earth is meant to be sort of a pre-modern world Eden; with the Hobbits being like Adam and Eve; and the name of the world Middle-Earth directly links Tolkein's world to mankind of course. And the heroes of Narnia are all people from our world. Tolkein's vision of Middle-Earth; a vivid fantasy world, parallel to our own; with all sorts of magical and mystical figures swirling together to create a sword and sorcery epic absolutely influenced Narnia; which is very much the same thing. And Lewis' efforts to use mythological figures as metaphors in a Christian morality play absolutely resonates in Tolkein. Lewis' stories were very much rooted in Christian themes, morality plays and biblical ideas; and while Tolkein's epic doesn't start out that way by the conclusion that is very apparent; as is Lewis' influence. Also Lewis embarked on a series first. The Hobbit came out first; but that was intended to be a standalone novel; and probably always would have remained that way; until Lewis devised his"Chronicles of Narnia"; which was introduced at the beginning of the series. The "Chronicles" were introduced before "The Lord of the Rings" was introduced. And unlike Tolkein who waited several years before writing a sequel; Lewis wrote one the very next year; so Lewis' concept of a series absolutely rubbed off on Tolkein. Also both writers use acronyms ofcouse; JRR and CS.