Eve was a mysterious and powerful being known by the title of Mother of All. She was in the depths of Purgatory, until she was released by dragons and arrived on Earth using a young virgin girl as a vessel. Like the Leviathans, with whom she was related to, Eve was part of existence before angels, which gave her an advantage over them, being able to inhibit them from using their supernatural powers, and possibly kill them.
Eve created the Alphas, which were the first monsters of their allotted kind from whom their entire species descended from. She created a worm-like creature, which Dean dubbed the "Khan worm". She also recently did what she called "Beta testing", creating creatures that Dean named "Jefferson Starships," which were monster hybrids that she mass-produced. Her only known weakness was that of Phoenix ash. She was killed by Dean, who mixed the ashes in his drink earlier, and when she bit him to turn him into a monster, she ingested the ashes and died. Her essence and what comprised her mortal form presumably returned to Purgatory after her death.
Powers and Stats
Name: Eve, Mother of All, Mother of Monsters
Age: Billions of Years Old (Predates the Angels)
Classification: Primordial Monster, Part-Leviathan
Powers and Abilities: Superhuman Physical Characteristics, Flight and Levitation, Immortality (Types 1, 3 and 4), Possession, Conversion (Capable of turning humans into monsters), Teleportation, Telekinesis, Telepathy, Power Nullification (Can render an angel powerless through her mere Presence), Advanced Biokinesis, Compulsion (Capable of controling her monster spawn through their mental link), Shapeshifting, Regeneration (At least High-Mid, possibly Mid-High, as angels who can controls matter at a cellular level can't kill Leviathans)
Attack Potency: City level (Above Angels and Seraphs. She depowered Seraph Castiel with her presence)
Speed: Unknown. Possibly Supersonic+ or even Massively Hypersonic (Powerscaling from Angels)
Lifting Strength: Unknown
Striking Strength: Small Building Class
Durability: Unknown, possibly City level (Regeneration and her true form's nature makes her hard to kill)
Range: Standard melee range for combat, Cross-Universal for Abilitites such as Teleportation and Telekinesis
Standard Equipment: None notable
Intelligence: Immensely High. She is one of the oldest beings in existence, having lived for Billions of Years. Holds a telepathic link to all existing monsters.
Weaknesses: Phoenix Ash