Darth Nihilus: True Sith Lord?
Is he truly a Sith or a Sith only in name?
Evidence Against Him Being A True Sith Lord:
Kreia: “And he cares nothing for the Sith or its teachings... or the Jedi. And when the Jedi are dead, he will feed on the galaxy, the Republic, and eventually, consume the Sith as well. There is no future in the empty galaxy he sees. And that is why he must be stopped; the breach must sealed, before his power grows beyond what even we can hope to stop. One cannot have power of that magnitude that her master possesses and still think and perceive the universe as we do, as most of us do.”
Kreia: "{Chiding} Power? Do you think so? {Shakes head} You would be wrong. There is no strength in the hunger he possesses... and the will behind his power is a primal thing. And it devours him as he devours others - his mere presence kills all around him, slowly, feeding him. He is already dead; it is simply a question of how many he kills before he falls.”
Evidence For Him Being A True Sith Lord:
He possesses a Sith holocron.
He is alongside other Sith like Lord Bane and Andeddu.
He is named Darth Nihilus (though NO ONE calls him by this in the game)