Reaper

Reapers were thought, for many centuries to be servants of death, and most importantly, to be neutral, mainly existing to serve the natural order and to bring death to people whose time is over. Reapers, however, were created by Azazel (Yellow-Eyed Demon) first, and were his creation. However, after a time, according to him, the reapers decided to join God's cause and abandon him. According to most every lore and myth associated with them, the reaper cannot be bribed. However, that was proven to not necessarily be the case--in 2006, a reaper was approached by Azazel. Azazel first asked the reaper to retrieve Dean Winchester's soul. When the reaper refused, Azazel put a different offer on the table: He told him that if he got Dean Winchester's soul for him and delivered him straight to hell, he could have whatever soul he wanted. The reaper agreed and appeared in the Iowa hospital where Dean Winchester was. The reaper started off with killing a few victims that were already due to die, and then went after Dean's soul. However, Dean stopped him--that time. The reaper knew that he had to try a different approach. Seeing as how Dean reacted with anger and fear at his true form, the reaper possessed the body of a dying, young girl named Tessa, the reaper posing as Tessa was almost too calm for Dean's liking but he didn't suspect anything until overhearing John and Sam discussing reapers and how, sometimes, they take the forms of others to lure their victims into a sense of security. He knew, then that he had been tricked and that Tessa was really a reaper in human form. He ran through the halls until he came to a darkened room where she was sitting, waiting for him.

She, acting on the orders of Azazel, convinces Dean to let go of his family, to move on. He does and she, fulfilling her duties to Azazel, delivers him straight into the pit. Though reapers are impossible to kill, John still had hope that he could have killed the reaper or at least found a way to kill it if he had known it wasn't there naturally. Reapers, though, are impossible to kill. They can be stopped for a certain period of time but they are virtually indestructable.

Powers-

Invisibility

Reapers are naturally invisible to the naked eye. They cannot be seen by any person they are trying to lure unless they choose to be seen. They are only, usually visible, to people when they escort them to their final resting place. The only beings that can see reapers are spirits as in the case of Dean Winchester when he was able to see the true form of the spirit and also the form of Tessa.

Teleportation

Reapers can appear anywhere on earth, in hospitals, wars, anywhere they choose to appear--or, wherever their next victim is. They also, in rare circumstances can appear in human minds--though this power is rarely seen.

Resurrection

Also rare is the reaper's ability to resurrect the dead. This is rarely seen because Crossroad Demons usually handle that part of things. Most of them don't bother with it, most see it as their duty to deliver souls to their resting place, not awaken them.

Terrakinesis

Reapers also possess the power of physically manipulating a room--as in, shaking it, causing it to fall apart, even. This can happen just from their presence sometimes.

Time Manipulation

Reapers can alter timelines, they cause objects that measure time to permanently break.

Astral Projection

Similar to angels of lore, the reaper can also project their astral form.

Superhuman Stamina

Reapers do not grow tired, and they will never leave their victims until they actually get them to cross over.

Invulnerability

There are ways to kill a reaper, but the only weapon to kill them is known as the scythe of death and a special incantation. The scyth, however, has not been seen and is rarely used and is currently not known to the Winchesters.

Killing Touch

Reapers possess the ability to kill their victims with a single touch, except for stronger beings, that is. The beings that are immune to this power are God, the four horseman and the archangels.

Telekinesis

Reapers can also physically manipulate objects or people. Similar to the way that spirits can move or throw objects or people, the reapers can do the same thing.

Immortality

Reapers are immune from dying. This includes hunger, disease or time.

Levitation 

In their true form, reapers have the ability to fly, hovering over their victims before taking them.

Perception Altering

In their true form, the reaper looks like a ghost almost when it floats above their victims just before taking them. Sometimes, in order to lure victims into a sense of security in their spirit form, the reapers will take on the appearance of another. In the case of Dean, the reaper took on the form of a young woman named Tessa, who was dying from an appendix surgery complication.

Healing

Reapers can and will heal a human, but the price for that is they have to then give the disease or injury they just healed, to another person.

Memory Manipulation 

Reapers can alter memories of humans, they can make them forget things and and they can also restore memories to a select person.

Intangibility 

Because in their true form they resemble a ghost, reapers also share many physical similarities to ghosts and can therefore pass through walls, doors and almost anything solid without any kind of impact or physical injury.