Shadra

"Wait, didn't I kill her in the Hinterlands?"

Loa are Wild Gods, and Wild Gods go back to the Emerald Dream when they die to come back later. See Cenarius, Aviana, and Goldrinn at Hyjal.

However when Yazma is draining Shadra she tells her to "Die forever!" so I assume Shadra's gone for good this time.

"While I have a negative history when it comes to Spiders, namely brought about when the Nerubians first came during Arthas' invasion of Quel'Thalas, I still held respect for Shadra's very nature as a predator meant to strike out of the shadows and sneak about to gather information. Knowing what your enemy is planning is a crucial tactic in warfare; even in these darker and more trying times that we all must face after the Legions' end, and Shadra the Mistress of Spies was no exception to this very nature. I was there when I saw Shadras' death; bound inside of her own sanctum as her blood and essence was devoured by her own High Priestess Yazma, and I could do nothing to stop it... Yet again: another immortal has died while I was unable to free my bonds and act to stop it..." - Chapter 5 of the Zandalar Campaign Journal, written by Gai'vahros Dawnbreaker of Silvermoon