How minor is minor? Like mentioned once? Completely obscure? Or a bit player in a longer story? Not knowing the parameters, I'll give you a few:
Eöl - unlike any other Elf Tolkien referred to in his whole corpus. Friendly with Dwarves, dark, malignant, proud.
Halbarad - the only Ranger I cared about besides Aragorn, and you have to go and kill him right off the bat. His death resounded in me as if he was a Game of Thrones character.
The Blue Wizards, Alatar and Pallando - so obscure they didn't even rate separate colors. What, you couldn't afford to give one a green cloak?