Krishna - The Dark Lord of Dwaraka

Veda Vyasa's Mahabharatha brought an astonishingly beautiful and complex character in the form of Krishna as the eighth Avatar of Lord Vishnu, the hero of the Mahabharatha, the Lord of Dwaraka, the charioteer of Arjuna during the Kurukshetra War, a statesman par excellence, a warrior without equal and finally the lover of the gopikas.
So in between all this, who is Krishna?

Primarily based on the Bhagawat Purana.