Who was the most evil of the characters?

As the name of the movie suggests,the characters all have a hint of evil in them.Some more,some less.Even the most righteous of the lead characters(the cop) has a hint of evil in him.But who was the most evil character of them all?For me the character of Kalki is the most evil.All the characters were dark before they met Kalki,but somehow she pushed them off the edge towards true evil.