You know who
I think is overlooked? Oropher. Father of Thranduil, King of Greenwood the Great, slain in the Battle of the Last Alliance. I'd like to know more about him. Also, I love his name.
I also think that Huor is overlooked a
lot. Most people just think, "Oh, yeah, Tuor's dad," or "Húrin's little brother." There
must be more to him than that! (see my post in the thread "Best MORTAL Fighter" to hear me rant about this injustice some more

)
And let's not forget the brother of Olwë and Elwë: Elmo!