Forgive me if this was stated on another reply in this thread (I don't have time to search through 80-odd pages), but I'm watching TNG right now, and it suddenly hit me:
Nan Bacco (I read all the books featuring her character earlier this year) - Ellen Geer.
She plays the woman who's convinced that Data collaborated with the Crytalline Entity in the fifth season episode "Silicon Avatar." All the while I was reading books with the Nan Bacco character in them, she was who I was picturing.