Question: Luthien, who appears in Tolkien's companion to The Lord of the Rings, "The Silmarillion", has her story told to Frodo by the heir of Isildur, who was first introduced by what name?

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Frodo Lives!: "Frodo Lives!"  was a popular counterculture slogan in the 1960s and 1970s, referring to the character Frodo Baggins from J. R. R. Tolkien's fantasy novel "The Lord of the Rings".  The term was used frequently in graffiti, buttons, bumper-stickers, T-shirts, and other materials.  It was commonly associated with the hippie movement.  Other examples of use include a "Frodo Lives" album released by Smash Records and merchandising items for the New Line Cinema "The Lord of the Rings" film trilogy.  The phrase was also displayed during the activation of a computer virus in the early 1990s, in which the text 'Frodo Lives!'  was displayed in large letters with a moving border.

Glorfindel: Glorfindel () is a fictional character in J.R.R. Tolkien's Middle-earth legendarium.  He is introduced in various material relating to the First Age of Middle-earth, including "The Silmarillion".  The name is also used for a character in "The Lord of the Rings", which takes place in Middle-earth's Third Age.  In late writings, Tolkien works out how the two characters were one and the same, though this is not evident from the published versions of "The Silmarillion" and "The Lord of the Rings".

Aragorn: Aragorn II, son of Arathorn is a fictional character from J. R. R. Tolkien's legendarium.  He is one of the main protagonists of "The Lord of the Rings".  Aragorn was a Ranger of the North, first introduced with the name Strider at Bree, as the Hobbits continued to call him throughout "The Lord of the Rings".  He was eventually discovered to be the heir of Isildur and rightful claimant to the thrones of Arnor and Gondor.  He was also a confidant of Gandalf and an integral part of the quest to destroy the One Ring and defeat the Dark Lord Sauron.

Frodo Baggins: Frodo Baggins is a fictional character in J. R. R. Tolkien's legendarium, and one of the main protagonists of "The Lord of the Rings".  Frodo is a hobbit of the Shire who inherits the One Ring from his cousin (referred to as his uncle) Bilbo Baggins and undertakes the quest to destroy it in the fires of Mount Doom.  He is also mentioned in Tolkien's posthumously published works, "The Silmarillion" and "Unfinished Tales".

The Lord of the Rings: A Reader's Companion: The Lord of the Rings: A Reader's Companion (2005) is a nonfiction book written by scholars Wayne G. Hammond and Christina Scull.  It is an annotated reference to J. R. R. Tolkien's "The Lord of the Rings".  Hammond and Scull proceed chapter-by-chapter from the original foreword through to the end of "The Lord of the Rings".  Appendices, examining the evolution of the text, changes, inconsistencies, and errors, often using comments from Tolkien's own notes and letters.  Other sections cover the numerous maps of Middle-earth, chronologies of the story and its writing, and notes on the book and jacket design of the first editions of 1954-55.  The book includes some previously unpublished material by Tolkien.  It also reprints part of a 1951 letter in which Tolkien explicates, at some length, his conception and vision of "The Lord of the Rings".  Reprinted for the first time since 1980, and corrected and expanded, is Tolkien's "Nomenclature of The Lord of the Rings" (previously referred to as "Guide to the Names in The Lord of the Rings"), an index of persons, places, and things designed to aid the translator in rendering Tolkien's work into foreign languages.  It is available in both hardcover and paperback.

Isildur: Isildur is a fictional character in J. R. R. Tolkien's legendarium.  He appears in the author's books "The Lord of the Rings", "The Silmarillion", and "Unfinished Tales".

Themes of The Lord of the Rings: Since the publications of J. R. R. Tolkien's The Lord of the Rings, The Hobbit and The Silmarillion, a wealth of secondary literature has been published discussing the literary themes and archetypes present in the stories.  Tolkien also wrote about the themes of his books in letters to friends, family and fans, and often within the books themselves.  In his Foreword to the Second Edition of "The Lord of the Rings", Tolkien said that he "disliked allegory in all its forms" (using the word "applicability" instead), and told those claiming the story was a metaphor for World War II to remember that he had lost "all but one" of his close friends in World War I.

House of Isildur: In the literary works of J. R. R. Tolkien, the House of Isildur was the Royal House of Arnor, Arthedain, Cardolan, Rhudaur and, much later, Gondor The house was descended from Isildur, elder son and heir of Elendil the Faithful.  Although the North-Kingdom was ended in the year 1975 of the Third Age, the House of Isildur was maintained as the Chieftains of the Dúnedain, the wandering folk that the Dúnedain of Arnor became, until the time of Aragorn II and the War of the Ring, after which, Aragorn claimed the Crown of Gondor as the direct descendant of Elendil.  After Aragorn, the House of Isildur became the House of Telcontar and ruled the Reunited Kingdom for generations.

Lúthien: Lúthien Tinúviel (Y.T. 1200–Y.S. 503; died aged 3377) is a fictional character in the fantasy-world Middle-earth of the English author J. R. R. Tolkien.  She is an elf, daughter of Thingol and Melian.  She appears in "The Silmarillion", the epic poem "The Lay of Leithian", the Grey Annals section of "The War of the Jewels", and in other texts in Tolkien's legendarium.  Her story is told to Frodo by Aragorn in "The Lord of the Rings".

The Tale of Beren and Lúthien: The Tale of Beren and Lúthien, told in several works by J. R. R. Tolkien, is the story of the love and adventures of the mortal Man Beren and the immortal Elf-maiden Lúthien.  (Early versions of the story, published in the standalone book in 2017, described Beren as a Noldorin elf.)  Tolkien wrote several versions of their story, the latest in "The Silmarillion", and the tale is also mentioned in "The Lord of the Rings".  The story takes place during the First Age of Middle-earth, about 6500 years before the events of "The Lord of the Rings".

Supporting paragraphs: Lúthien Aragorn
Answer: Strider at Bree