Spectre Saren Jahatai Arterius, also known as Saren, was a Turian Spectre (leader) of the infamous Andromeda Treaty, one of the three members of the Spectre High Council, and the chiefest of the three Spectres. He was the head of the Treaty Council, and the political leader of the Treaty. In a sense, Saren made all the major decisions of the Andromeda Treaty, including the decision to attack the Sol Alliance (Mars and Earth). He personally oversaw the slaughter of billions along with his fellow Spectres, Krebb and Wrex.
Saren is one of the most hated figures in all history, because of the terrible deeds he and the Treaty wrought upon the Milky Way Galaxy, as well as his own galaxy, the Andromeda. He is cold, tactical, unforgiving, swift, brutal, and immensely intelligent. Under his leadership, the Treaty laid waste to countless worlds, and harvested equally countless stars.