Sometimes in metaphysics you will come across the phrase "dark angel." There are many interpretations of what the dark angel means when it comes to the psychic arts. Some of them are more psychological and other is more cultural.
The most common interpretation of the dark angel is Lucifer. Lucifer is one of the original favorites of the Archangels in heaven and he fell from grace. In essence, he was kicked out of heaven for misbehavior, but got to keep his angel wings. You often see depictions of Lucifer in angel art. He is one of the earliest players when it comes to the religious angels mentioned in the bible. Of course, if you are a practicing Satanist, you will never be asking your self if Lucifer is "angels or devil." The angel falls from heaven myth is absolutely crucial when it comes to studying the pantheons of angels and also drawings of angels. Lucifer is also one of the original natural angels, which is why he so often appears in angel art.
The feminine version of the dark angel of love is Lilith. Lilith is often described as a first wife of Adam that is not mentioned in the Bible. As she was not made from man's rib, she became corrupt and was thrown out of the Garden of Eden. She is not mentioned in the Bible, but she is honored with some sects and even feminist sects that see her as the original earth mother. She is one of the amour angels in the sense that she symbolizes seduction.
Yet another interpretation of the dark angel is as a description of a lover. This could be a karmic relationship that is somehow troublesome or bad for you. The dark angel of love is someone in your life who you can not stop thinking about or becoming obsessed about. It is the relationship that you are unable to handle or that causes you great grief. If you are a man, this dark angel is no doubt the "Lilith" in your life.
However, in contemporary times, most of us know the Dark Angel as a television series directed by James Cameron that ran from 2000 to 2002 on Fox television. The Dark Angel character was a genetically enhanced super soldier played by actress Jessica Alba. She escapes from an oppressive government institution and trains to be an assassin with eleven other genetically enhanced human beings. Originally, this dark angel was supposedly to be a film, but James Cameron could not get a film deal to support it. It is important culturally as the character paved the way for several more superwoman type characters.
Yet another common meaning of dark angel is the concept that it simply describes the dark side of you that succumbs to temptation. It is your shadow side that insists on not being connected to the light.