Over the years, the Winchesters (and their family and friends) have encountered a plethora of monsters. Some monsters come back several times over time, and we can recognize them enough to try and figure out the clues before Sam and Dean do. By the same token, some of our friends have become “monsters” (*)and have either needed to be ganked or go on to live very productive lives with spouses and children. You never know what you’ll find in a Supernatural episode. Also, my use of the term monster (*) includes entities like Angels or other neutral/good or not-necessarily-bad characters.
Here are a few of their favorite monsters:
Angel. See also Archangel.
Bisaan (episode: The Chitters)
Demon. See also the Yellow Eyed Demon, Crossroads Demon, Knight of Hell, Meg, Ruby, Lilith
Eve. See also Mother of All.
Ghosts. See also Vengeful Spirit, Poltergeist
Trickster. See also Loki.
Vampire. See also Alpha Vampire.
Witch. See also Rowena.
Monsters they’ve named: Jefferson Starships, Khan worms