Black Lantern: Flats

Lyssa Drak is best known as one of the eye candy of the Sinestro Corps and during the Blackest Night crossover she ended up absorbed into the Book of Black which was created by the undead Guardian Scar.

Afterwards she was forgotten for a while until she was released by Krona for the War of the Green Lanterns. She is still using a yellow power ring in the latest Green Lantern comic, but she is a complete follower of the Book of the Black which are prophesies from Nekron. Which in my mind makes her the last member of the Black Lanterns active.