The famous Elvish sage of Tirion, creator of the first system of letters, the Sarati (S/63, WJ/396). He was also the author of the Ainulindalë (MR/8) and other scholarly works. The meaning of his name is unclear.

Conceptual Development: This character first appeared in the earliest Lost Tales, where ᴱQ. Rúmil was the door warden of Mar Vanwa Tyaliéva (LT1/46-7), but even at this early stage he was identified as a sage (LT1/65). In Silmarillion drafts and notes from the 1930s, ᴹQ. Rúmil was described as the Elf-sage of Valinor and he wrote the first part of the Annals of Valinor as well as the Ainulindalë (LR/116, 156). He also wrote the linguistic works on which the Lhammas was based (LR/167).

J.R.R. Tolkien never explained the etymology of this name, but Christopher suggested that the earliest forms of this name might have been related to G. rûm “secret, mystery” (LT1A/Rúmil). A similar name Rumel appeared in a list of “ancient compounds” in some linguistic notes from the early 1930s (PE21/33), but without any further indication of its meaning.