I'll offer this for the letter "I".
Ithryn Luin - the two Blue Wizards who were lost in the East long before the War of the Ring. Their names were Alatar and Pallando.
I was going to say Istari, but it just lands us back in the same position with "I", so hopefully since there were two Blue Wizards they can be a very small race unto themselves.
I rather like the idea of this thread, if it can get off the ground. It might develop into an interesting little game.
Sophia