Death Alert

ServerScriptService

local ReplicatedStorage = game:GetService("ReplicatedStorage")
local remoteEvent = ReplicatedStorage:WaitForChild("RemoteEvent")

game:GetService('Players').PlayerAdded:Connect(function(player)
    player.CharacterAdded:Connect(function(character)
        character:WaitForChild("Humanoid").Died:Connect(function()
            remoteEvent:FireClient(player, player.Name)
        end)
    end)
end)

StarterPlayerScripts

local ReplicatedStorage = game:GetService('ReplicatedStorage')
local remoteEvent = ReplicatedStorage:WaitForChild('RemoteEvent')

textColor = BrickColor.new('Really red')

local function welcome(playerName)
    game.StarterGui:SetCore('ChatMakeSystemMessage', {
        Text = playerName..' has died';
        Font = Enum.Font.SourceSansBold;
        Color = textColor.Color;
        FontSize = Enum.FontSize.Size24;
    })
end

remoteEvent.OnClientEvent:Connect(welcome)