Ilkorin had several distinct dialects. Tolkien mentioned two by name: Falathrin or Falassian spoken by the Elves of the havens of Falas and Doriathrin spoken by the subjects of Thingol in Doriath (LR/170, 175). Tolkien also sometimes used the term Beleriandic, but this seems to have simply been a term for the languages of Beleriand in general rather than a specific dialect.

Tolkien designated quite a few words as simply Ilkorin (Ilk.). It is unclear whether these represented a third dialect spoken by Beleriandic Elves outside the two regions mentioned, or whether it was simply a term for words common among all dialects. If it was a distinct dialect, it probably belonged to the “other scattered companies of the Ilkorindi that wandered in the land, but these have all perished” (LR/175), so that only the Falathrin and Doriathrin dialects survived the fall of Beleriand (LR/178). For purposes of discussion, generic “Ilkorin” is treated as its own dialect here.