In ‘The Lord of the Rings’, Legolas primarily speaks Sindarin, one of the two main Elvish languages created by J.R.R. Tolkien. Sindarin is often associated with the Grey Elves and is characterized by its melodious quality and rich vocabulary.
Legolas, being a member of the Wood-elves from Mirkwood, would communicate in this language as it is prevalent among the Elves of Middle-earth. While there are other Elvish languages such as Quenya, which is more formal and ancient, Sindarin is the language most frequently used in daily conversation among Elves in the narrative. You can notice Legolas’s use of Sindarin in various dialogues throughout the series, showcasing both the beauty of the language and the depth of his character.