Cursed. Your nature has been utterly perverted. Even when you are resurrected, you return to this undead form. You function as any other living being otherwise.
Unliving. You are immune to disease, and are resistant to poison damage and have advantage on saves against poison. You do not need to sleep, eat, or breathe.
Undead Fortitude. When you are reduced to 0 hit points but not killed outright, you can drop to 1 hit point instead. You can’t use this feature again until you finish a long rest.
Languages: You know the languages you knew in life
If using a limited number of deaths in your campaign, consider one of the two options as a cost for this Template. Lower the number of deaths the character has by 1, or, consider that they became undead through ritual rather than by death and reanimation.