[Ending Spoiler]
I'm just going to start off by saying that I fully expected Lelouch to die, but I didn't expect him to plan to die. Not only did he choose to die for his plan, but his assassination was carried out by his best friend and those close to him were in on it. Not only that, but Nunally realized his plan as he was dying as well which just made it even more sad. I had to try not to shed a tear, I was honestly so sad.
Sorry for the paragraph but I'm also pretty sure he's not actually dead. I think he might have taken C.C's code and fulfilled their contract before he carried out his final plan.