The Seven Satans, also know as the Seven Sins or Seven Deadly Sins, are the seven angels (eight, if you consider Astaroth and Astarte as two separate people) that followed Lucifer in his fall from Heaven. They each represent a sin.
“One of the Seven Satans, the Golden Count, "Avarice", formerly a member of the Angels. He was...Mammon
“The Seven Satan of "Envy". He was once an angel who sheds his angel-hood and dons the cloth of a...Leviathan