This is a spoiler zone for anyone that wants to watch Attack on Titan (Season 1 and/or Season 2) and Fullmetal Alchemist 2003/2009. You have been warned.

Here's a space for those that want to leave:

Winner for this is Mike's Death from Attack on Titan.

It was no surprise; I saw it coming. And yet his eerie screams and the Beast Titan's line "so you can speak!" makes it all the worse.

Plus, Mike is my favourite AoT character.

Honourable Mention:

Carla's Death (Attack on Titan) (AoT has lots of brutal deaths)

Tucker's Chimera Reveal (Fullmetal Alchemist):

(Only FMA fans will understand why this cute doggie is not so cute)