How to detect if an NPC is dead?

I'm working on a game, and I'm making the final boss. I want it so when the boss dies, it awards a badge. Problem is, I'm terrible at scripting and it's not working as intended, though I've referenced many wiki pages.

local humanoid = script.Parent
local BadgeService = game:GetService("BadgeService")
while true do
	if humanoid.Health < 1 then
		BadgeService:AwardBadge(2124549136)
		print ("Beat Game")
	end
end

Additional info: Localscript inside of Humanoid of an NPC If you could help, it would be greatly appreciated.