Hael

Hael was an angel that was sent to kill Metatron.

History
According to her, she built the Grand Canyon when she was last on Earth and told Metatron she was gonna go visit it after she's done with him. Hael also states that her and Bernael are twins, with Bernael only being born a few minutes before her.

Season One
While never seen, Bernael talks about her a couple times and Haziel even talks to Bernael about her.

Season Two
When Metatron was found out to still be alive, Michael sent Hael to take Metatron to him or kill him on the spot if he puts up a fight. She went to Haziel and Rebecca to learn where Metatron might be. Alex Long tried to attack her and when she stabbed her with a kitchen knife, Hael sighed in annoyance and pulled the knife out, she then sedated Alex. When they wouldn't tell her, Hael left and met up with Bernael, who told Hael where Metatron was after having a large meaning conversation with her. Hael went to Metatron and when she showed up, she killed a group of demons protecting him. Metatron and Hael get into a fight and Metatron ends up killing Hael with her own angel blade.

Powers and Abilitites
Hael was a Seraph and is said to be as powerful as Bernael once was before his addiction to angel grace.
 * Angelic Possession - Like all other angels, Hael required a vessel to walk the Earth and needed their permission.
 * Biokinesis - She caused pain to Rebecca's internal organs by cluching her fist. She also gave Rebecca back her cancer and sped up the process. She even took away Alex's lungs after waking her up.
 * Healing - Upon leaving Rebecca's house, she healed her of all her wounds and re-cured her cancer. And gave Alex back her lungs.
 * Immortality - Hael was thousands of years old when she died, old enough to have created the Grand Canyon.
 * Terrakinesis - Hael was able to carve the Grand Canyon out with her powers thousands of years ago.
 * Telepathy - Hael could hear "angel radio" and broadcast on it.
 * Smiting - She smited a group of demons trying to protect Metatron.
 * Teleportation - She could teleport anywhere she wants instantly.
 * Sedation - She rendered Alex Long unconscious with a touch.
 * Invulnerability - She was stabbed by Alex Long and pulled it out, and just sighed in annoyance.

Weaknesses

 * Angel Blade - An angel blade could kill Hael.

Season 2

 * Heaven above, Hell below

Trivia

 * Her name means "The God" in Hebrew and in Jewish sources.
 * The name Hael also means "Angel of Kindness." Hael is said to inspire art, beauty and kindness in mankind.