* Old English: This was one of his primary areas of study, and his expertise in Old English was instrumental in his later work, particularly in the creation of the languages of Middle-earth.
* Gothic: This ancient Germanic language fascinated Tolkien, and he wrote a dissertation on it. It influenced his development of Elvish languages.
* Finnish: Tolkien was deeply impressed by the structure and beauty of Finnish, and he credited it with inspiring his invention of Elvish languages.
* Latin: As a scholar of medieval literature, Tolkien had a strong foundation in Latin.
* Greek: Similar to Latin, Tolkien studied Greek as part of his academic background.
* French: Tolkien learned French during his time in school.
* German: Tolkien had a strong knowledge of German, which he used extensively in his academic research.
Tolkien's linguistic knowledge extended far beyond these core languages. He was also interested in and familiar with a wide range of other languages, including Welsh, Old Norse, Old Frisian, and even languages like Esperanto and Volapük. This deep understanding of language influenced his writing in profound ways, shaping the complex and nuanced languages of Middle-earth.