Since the war started, I myself is kinda wondering if this will be an exception in Oda's non-killing policy. So i kinda wanted to make a list of those who got taken out in this war. Of course, not counting all the nameless characters.
I just want to remind you that this list consists of those suspected to be dead until proven alive. And if I'm missing anyone, please add.
So here goes:
1. Bentham a.k.a Mr.2 Bon Clay. Chap 548 : opened the Gate of Justice for Luffy n co by disguising himself as Magellan. His fate is still unclear as of now, and even though this happened before the actual war, but in a way he "died" to help Luffy and the others to reach the actual war. Plus I think you would all agree even if he is put in this list "just" for honorable mention sake.
2. Oz Jr (or Oars Jr, depending on whose translation). Chap 556 : hit by Kuma's Ursus Shock, got his leg cut by DoFlamingo and impaled by Moria. Nuff' said. Though this happened in chapter 555, but his actual fall is in 556
3. Vice Admiral Ronze. Chap 556 : Whitebeard sent a quake right inside his helmet. I dont think anyone could have to survive that.
4. John Giant. Chap 564 : Whitebeard sent a quake that went right through his heart.
5. Whitebeard 13th Division Commander "Water Buffalo" Atomos. Chap 556 : Last seen being controlled by DoFlamingo. Though still unclear what happened to him, but we have never seen any shots if him since
6. Whitebeard 10th Division Commander Curiel. Chap 562 : Last seen being was fighting Moria, still unclear what happened to him but we have never seen any shots if him since
7. Vice Admiral Lacroix. Chap 555 : Got hit my Oz Jr. Judging from the panel, I'd say that he is a giant, and not the one with the mustache