In Memoriam

Angels granted the power to erase memories and subsequently, the powers of other angels. It is not so much exactly a 'type' of angel, but a job. Any angel can become a nemosyne, provided that they have the abilities to do so.

They're easily distinguishable by their metallic markings - meant to mimic the natural markings of Lucifer. Metatron is the exception of this, namely because he did not choose to be the leader.

Not quite angels, not quite demons. Their connection to Heaven is strained - one minor change could irrevocably turn them into demons.

Demons are split between angels whose connection to Heaven has been completely severed and beings born from heavily intense, negative emotion. 

Spawn between a human and an angel. Nephilim are considered a threat by the archangels and any that are noticed are quickly exterminated.