I have been using this feature for a long time, but I thought I would like to share it with everyone. It is very easy to use, and lets you add a death counter on your server.
First open you chat field and write
/scoreboard objectives add Deaths deathCount
It should now write “Added new objectives ‘Deaths’ successfully”
Now write: /scoreboard objectives setdisplay list Deaths
It should now write “Set the display objective slot ‘list’ to ‘Deaths'”
If you now press “tab” to view who is online, there is now a number next to their name. Every time a player dies it counts it, and add it there.
If you rather want the death counter to always be shown. Write: /scoreboard objectives setdisplay sidebar Deaths
It should now write “Set the display objective in slot ‘sidebar’ to ‘Deaths'”. The Death counter should now always be shown at the right side of your screen, as on this screenshot.
I hope you enjoyed this game. If you have any questions, feel free to tweet at me as always.