9. Galuf - Final Fantasy V
Look, so we all know about Aerith's death in Final Fantasy VII - even people who have literally never even considered playing the game before. It's also quite common for people to call her death a plot hole, as her death takes place in a world where, when a character dies in a fight, you can just give them a Phoenix Down to revive them.
But, in all fairness, Final Fantasy justifies this death by claiming Aerith's spirit refuses to come back to the world of the living, having bonded with the Lifestream.
So anyone who's still confused or even annoyed over Aerith's death could also spare a moment for Galuf, who faces a similar fate in Final Fantasy V. Admittedly, Galuf does kind of get a cooler death, as he literally faces off against the final boss of the game by himself and while at 1 HP in order to protect his grandaughter.
While this context makes his death more logical - as when the party try and use items to revive him, they fail as he's too far gone, having pushed basically past the point of death while fighting - it doesn't make it any less sad when he goes.