"Are you under the impression that family's supposed to make you feel good?! Make you an apple pie, maybe? They're supposed to make you miserable! That's why they're family!" -—Bobby, speaking to Dean

Season - 1 - 7
Race - Human (formerly), Ghost
First appearance - "Devil's Trap"
Last - "Survival of the Fittest"
Powers - Superhuman strength, intangibility, teleportation, invisibility, telekinesis, and possession as a ghost
Appeared In - 54 Episodes
Status - Deceased (died from a brain injury as a result to being shot by ♥♥♥♥ Roman)
Occupation - Hunter
Affiliation - Winchester Family
Location - South Dakota (formerly)
Portrayed by - Jim Beaver

Robert Steven "Bobby" Singer was a hunter, close friend, and over-time evolved into a father-figure to Sam and Dean Winchester.

Personality
Bobby is a hunter like the Winchesters, though he seems to stay fairly stationary. He wears a lot of flannel and is almost always seen in a trucker's hat. He runs an auto salvage yard as his day job, and is a go-to guy for supernatural research.
He seems to have amassed quite a bit of knowledge over the years (being the first to deduce on his own that Meg was in fact possessed), plus his house is full of bookcases and stacks of books about the supernatural world and the things hunters go after. He and John Winchester were old friends, though they had a falling out prior to the onset of the series.

After John's death, Bobby becomes like a father to Sam and Dean. He was very loyal to them and cared for them deeply like they were his own.

Skills and abilities
As a ghost
Ectoplasm Secretion - Bobby caused a tear of ectoplasm to appear in the corner of the eye of the housekeeper he possessed.
Invisibility - As a ghost, Bobby is naturally invisible. However, as he grows stronger, is able to make himself seen and unseen at will.
Intangibility - As a ghost, Bobby is naturally intangible. However, as he grows stronger, he is able to make contact with things at will. Originally, he needed to become very calm, but as he grows more vengeful, the ability comes easier.
Possession - Bobby was able to overshadow and take control of a housekeeper.
Superhuman strength - Bobby is physically stronger than he was as a human. He was able to knock ♥♥♥♥ Roman to the ground.
Telekinesis - Bobby can impart kinetic energy on an object with his mind.
Teleportation - Bobby can travel from place to place without occupying the space in between. However, he is tethered to his flask.
Thermokinesis - Bobby was able to drastically lower the temperature in the room, causing a mirror to freeze over.