I'd say it's definitely a matter of belief. This is most certainly up to your specific religious views whether or not "he" exists.
The concept of Death coming for you is much older than the infamous Grim Reaper. Grim, meaning deathly or depressing; and reaper, meaning to gather or collect. He is a "personification" of Death. Death can be seen as a spirit or entity.
Grim Reaper was not originally designed after the Death in Chinese fables that would come for elder men and women that feared him, the stereotypical Grim Reaper, while functioning as death, was actually modeled (in appearance) after the guardian of Hell's gates, or that of an Underworld form of afterlife.
An example would be Charon or Uriel.
So like I said, this entirely up to your beliefs. No one can tell you not to believe he exists, and no can tell you to believe he exists.
While one can choose which if any personification they can choose to believe in, in spirituality, specifically necromancy, spirits and energy of Death are a pretty large staple, so while that may not make it "true", that could be applied to any topic in the supernatural.
I'd have to say the Grim Reaper is the representation of death. He takes your soul from your body using his blade. He is not evil more of a messanger. He takes you to be judged. He wear a robe to show his placement and how he lives in the shadows of our lives. Some call him the angel of death but that's more of a religious view in my eyes. You can blame him all you want but I think something caused him his job of collection the souls to create the dead.
i believe fully in the grim reaper i think he is a natural being as well as a dark being i feel that he is the king of death rulerof necromancy and simply controls the unerworld would i fear probobly not but i would love to meet him i think people could learn from his wisdom
Many gods could be held responsible for the Concept of a Reaping figure.
Thanos, Nammtar to name a few. Or demi gods such as Charon.
Other beings such as Azreal the Angel of Death are said to appear skeletal, similar to the Reaper concept.
Such beings are psychopomps with a stigma, the human fear of Death twists the image to a fearsome one, when a skeletal frame is truly only a reflection of the Truth of human Mortality.
Quite many cultures agree on angels and demons, or similar figures, predating Judaic deity. This could be taken as such, that there is a "figure" of Death that assists the transition. This Does not mean such a being is evil, negative, or has unlimited power, rules a realm, lords the underworld, I
t even had vast necromantic secrets as those whom expect would see them.
Such a figure would simply Be, existing in its own way as Death itself does.
An embodyment of Threshold state, between one existance and the next.
Such is my view. It need not be yours. As with gods, there can be Many concepts or personifications of a concept such as Death.
in many story's about the grim reaper or death is that he is an equal to god or gods on a grand scale and the he is more of a follower than a creature as are his capability meant to be.
He is widely recognised the same way through out many religions and story's of him as an angel or Reaper(some times both).
not to mention he is also meant to be the only being that has an equal or greater sense of justice than god.
In Catholicism he refuses to destroy the Babylonians because he thinks they can be saved and "god would not listen to reason" (Catholicism in a nut shell(I'm catholic in-case you're offended))
like it has been mention the reaper is not omnipresent however he is omnipotent and a man of his word. when ever he say's he will do something he will keep his word unless it contradicts what he was told in the first place.again he was told the Babylonians we not able to be saved yet the reaper saw that they could be if they were given a reasonable chance.
Don't forget the whole idea that if you can beat him at a game you can win your life back he always kept his word in every story. also he is the only figure in any religion/faith/story that he is the only figure with a sense of humour about his
job(s)
p.s message if you would like to talk about the grim reaper. in- case you didn't catch on I'm a little obsessed with the idea's of him.