The Death Patron: Pact of the Grave warlock subclass is an interesting example of how to incorporate Death itself as your patron. The basic premise is that, having died, Death believes you should return to the Material Plane and serve her by killing or reviving individuals. You get a good chunk of new features, including an undead familiar, death-based spells, abilities similar to undead creatures, invocations that allow you to speak with or control the dead, and optional death-based magical items. Also included in this PDF are Death Warlock and Undead Familiar NPCs as well as some decent lore related to the subclass.

Overall, this is a really interesting idea, but it does seem a bit messy. There are quite a few typos and inconsistencies within the supplement, including how to create undead or control them, and it will take some definite work to make everything line up. Your DM might also think that you have too many options and try to reign some of them in. However, I do think this is worth looking into and a good option for anyone that wants to play a character related to the undead but doesn’t want to be a necromancy-based wizard.

I love the idea of this patron, however i got rid of the second level spell "gentle repose" because it really does no good at such a low level, i changed it out with "spare the dying" cantrip (which is much more fitting) as a bonus cantrip that does not count towards cantrips known. Also an actual familiar list would be helpful, im having a really hard time figuring one out.... otherwise its a great class supplement!