Bilbo Baggins says “All that is gold does not glitter” in The Lord of the Rings.
The lines appear in a poem about Aragorn that Bilbo wrote or preserved, and they serve as a clue to Aragorn’s hidden identity and worth. The complete verse contrasts outward appearances with inner value and hidden strength.
Bilbo is the protagonist of The Hobbit and the older relative who gives Frodo the Ring at the beginning of The Lord of the Rings. By the later novel, he is living in Rivendell and spending his time writing, studying, and translating old lore.
The quotation is sometimes incorrectly attributed to Aragorn because it describes him. However, the character who composed and recites the poem in the relevant context is Bilbo Baggins.