Undertaker

The Undertaker is an NPC that will spawn once the following conditions have been met: If the Undertaker is killed, he will only respawn if the above conditions are met again. He uses Lunar Flares to defend himself.
 * There is an empty house.
 * The Trinity has been defeated.

Names
The Undertaker can have the following names:
 * Tenner
 * Geyer
 * Cleve
 * Ferron
 * Gasper
 * Spots
 * Hargon

Quotes

 * "Don't worry. Nobody will get out of the coffin that I have made."
 * "Are you afraid of ghosts? I'm not. But the ghosts are afraid of me."
 * "If you need some help then feel free to ask me. I have a lot of undead things on my side."
 * "What will you prefer to do if this day will be your last day?"
 * "Our life is a challenge. To make it easier - buy my stuff."
 * "Don't worry. I'm not a vampire even my eyes are red and my skin is of a strange color."
 * "Do you prefer blood or tomato juice?"

Trivia

 * The Spear of Justice may be a reference to Undyne's Spear from a game called "Undertale"
 * Skull Heart may be a reference from a game called "Skullgirls"
 * Living Tombstone may be a reference to the youtuber "The Living Tombstone"