The Grim Reaper

The Grim Reaper is a pre-existing Sim, and a master of the forces of life and death who can also seduce people.

He has appeared in almost every episode of Season 1, and several times in Season 2. The Grim Reaper only appears when a character dies. In Season 1, he was responsible for reaping the souls of the victims murdered by the Demon Packs, as well as Rosalina and Fox, in the Season 1 Finale he reaped the Animatronic Mafia' s souls. In Season 2, he has reaped the soul of Squidward Tentacles after he drowned, Patrick Star's soul, and several other characters.

In the Season 2 Finale, he reaped the soul of Squidward Tentacles after Ayano Aishi and Karen Devilish murdered him in a gory yet funny fashion.

Personality
His personality does remain largely unknown, even in Season 2, although there is one trait known, which is the Incubus/Succubus trait as he has the ability to make those around him flirty, this fails as of Season 2 as Queen Boo does not get flirty when The Grim Reaper reaps the soul of Squidward.