Pol Pot? - millons killed in the ruralisation projects Mao Zedong? - millions killed or imprisoned in the "cultural revolution" Joe Stalin?- millions killed in the purges and post war gulags.
Not even close. Actually many of the practices of the Nazis towards the Jews was what the Ottomans had done to the Armenians about 20 years before. Unfortunately genocide has been, and still is a human problem. Just look what has been happening to the Kurdish people over the last couple of decades.
We should definitely never forget what Hitler did but no sadly not the only evil that has existed.. I hear tale that Saddam wasn't exactly kind to his people too.