Aloastair

Aloastair (occasionally spelled "Alistair") was a powerful Greater Demon who was Hell's grand torturer and chief executioner to the monarch of Hell, and Meg apprenticed under him in the field of torture. He was able to travel from Hell and Earth with incredible ease, something he shares with Azazel. His stature to Lilith is vague, but the way he grudgingly followed her orders indicates that she at the very least out-ranked him. Mia first encountered Aloastair in Hell and he is the one in charge of torturing him.

During the 40 years (or 4 months in Earth time) that Mia was in Hell, each day Aloastair would ask Mia if she wanted to trade her place for another soul. For the entire 40 years, she refused and, each day, was chopped and killed and then placed back together, only for the cycle to continue.

Powers and Abilities

Aloastair was one of the most powerful demons to appear on the show. He casually overpowered hunters, reapers, and likely other lower-level demons. Even in a weakened state from the injuries he sustained from the prolonged torture at Mia's hands, he could still overpower a lower-level angel—an impressive feat, considering the differences in strength between ordinary demons and even lower-level angels. Aloastair belongs to the highest hierarchy of Hell, although he was still subservient to Lilith. His arrival caused a church statue of the Virgin Mary to weep blood in "I Know What You Did Last Summer".

• Immunity: Aloastair could not be killed by smiting from a lower-level angel. He was immune to iron and able to walk on holy ground. Alastair was also extremely resistant to a Demon Killing Knife as it only caused him mild pain rather than the agony most Demons feel.
• Invulnerability: Aloastair withstood would-be fatal injuries such as numerous stabbings and prolonged torture with little reaction.
• Telekinesis: Aloastair had the ability to move objects with his mind. He used hand gestures to drag and throw people over large distances without physically touching them. During his first appearance, he also blasted apart a door without noticeable use of gestures.
• Torturing: Aloastair was an expert in how to torture humans and demons alike. His skills at torture was such that even other demons feared him, nicknaming him "Picasso with a razor." Because of his prowess, Aloastair was often issued special assignments in torture, including breaking Mia and even Sidney's souls in Hell and interrogating Ariel.
• Teleportation: Aloastair could teleport from one place to another, including travel between Hell and Earth. He appeared directly behind Angel in "Heaven and Hell", despite there having been nobody there even seconds before that. He did the same to Buffy in "Death Takes A Holiday" and "On The Head Of A Pin"; in the latter episode, he even slipped out of a number of chains binding him without making them make noise from his escape.
• Immortality: Aloastair could potentially live forever. Although his exact age was not revealed, he considered Ruby, who was over seven hundred years old, to be a young demon.
• Knowledge of Magic: Aloastair knew an exorcism which expelled lower-level angels from their vessels; he tried to use this exorcism on a Cassiel in "Heaven and Hell" and again in "On the Head of a Pin", but was interrupted both times. He also knew Enochian sigils which warded buildings against angels, and a spell which incapacitated reapers. Additionally, he had knowledge of the 66 Seals and how to break them.
• Biokinesis: Aloastair directed a psychic attack on Buffy and Dawn simultaneously in "Heaven and Hell" by raising his hand at them; causing them to grip their chests and fall down, implying that he was attacking their hearts, or lungs.
• Healing: Aloastair possessed the power to repair wounds, as Mia described having been repeatedly torn apart and then completely restored under Aloastair's charge in Hell.
• Possession: Aloastair used a pediatrician as his vessel in "I Know What You Did Last Summer" and "Heaven and Hell". When Ariel regained her grace, the light she emitted destroyed the pediatrician, forcing the demon to claim a new vessel when he returned to Earth in "Death Takes a Holiday". He soon fled this vessel and possessed a third man, whom he continued to possess until they were both killed in "On the Head of a Pin".
• Flight: In his true-demonic and disembodied smoke form, Aloastair could fly.
• Supernatural Perception: Aloastair perceives beings that are invisible to humans such as ghosts, demons, and reapers.
• Supernatural Stamina: Aloastair had an incredibly high pain threshold, withstanding hours of extreme torture from Uriel and later Mia without giving up any information. When he got free, he showed no signs of weakness or exhaustion despite multiple injuries to his vessel.
• Supernatural Strength: Aloastair was an incredibly strong demon, able to overpower both low level angels and demons with relative ease. Aloastair lifted and strangled Mia with one hand without any signs of strain. He also lifted a low-level angel and placed him on a hook while they were both in vessels.
• Regeneration: While being tortured by Mia, Aloastair claims to have coughed up his throat but was still able to continue speaking with no noticeable change.

Weaknesses

Aloastair had very few true weaknesses. He was one of the strongest and most durable demons ever to exist.

• Devil's Trap: Like all demons, Aloastair is rendered powerless within a devil's trap. However, his resilience and endurance remain present.
• Higher Demons: Despite being a powerful demon in his own right, he was subservient to demons ranking higher than him. Lilith could easily send Aloastair whenever and wherever she wanted.
• Archangels: Only angels of the greatest power could effectively destroy Aloastair. Regular soldiers are unable to smite, or even defeat Aloastair. Even the projection of Anna's true form merely obliterated his vessel but did not cause fatal damage to the demon himself.
• Heavenly Host: Multiple Angels acting collectively could capture Aloastair in a special unknown manner. 
• Death's Scythe: This weapon is capable of killing all beings, even Death itself according to rumors, with ease.
• Holy Water: Although highly resilient to it, it still caused him pain. However, holy water was not enough to stop or seriously bother him.
• Salt: Although resilient to, it still caused him pain.
• Hex Bags: Aloastair cannot locate someone if they are concealed by hex bags.
• Angel Blade: As an angel blade can kill at least most demons it likely could kill him or at least hurt him.