Who is the Renegade Dalek Supreme?

The Renegade Dalek Supreme is perhaps one of the most iconic Dalek leaders in the history of Doctor Who. As the leader of the Renegade Dalek faction, this Supreme directed his forces against Davros' Imperial Daleks during the Imperial-Renegade Dalek Civil War. But what is the story behind this distinctive Black Dalek? And is it possible that we had actually seen this Dalek before the events of Remembrance of the Daleks?
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