Crowley's real name is Fergus Rodrick MacLeod.

Lucifer has used Nick, Castiel, and Sam as vessels -- but never Dean.

God, initially known to Sam and Dean as Chuck Shurley, is a powerful primordial being who created the universe and nearly everything it contains.

In "Bad Day at Black Rock", after losing an unlucky rabbit's foot, Sam steps in gum -- then loses his shoe down a drain.

Donna Hanscum is the sheriff of Stillwater, Minnesota. She was married to another sheriff named Doug who left her because of her weight.

Jody Mills was the sheriff of Bobby's hometown of Sioux Falls, South Dakota. She had a son, Owen, who died and came back as a zombie during the Apocalypse. At first, she tried to prevent Sam and Dean from investigating, but when her son killed her husband, she worked with the Winchesters to kill the remaining zombies.

Amy pond is a kitsune, a werewolf-like monster that feeds on the pituitary gland, a part of the brain, without which they will die. When Sam discovers her secret, he lets her go because she saved his life. Years later, Sam notices similar killing happening again, and tracks Amy down.

Jessica Lee Moore was Sam's girlfriend at the start of the series. He planned to ask her to marry him, but she was killed by a demon.

A daeva is an ancient demonic creature of shadow that can be summoned by other demons. Like hellhounds, daevas are used as invisible killers. While they are invisible, daevas appear as humanoid shadows.

Eldon Styne is the heir to the powerful Styne Family, a dynasty that causes and takes advantage of disasters such as the Nazi rise to power and the September 11th attacks to make a profit. Like all other members of his family, Eldon has received surgical enhancements including a second heart.