It would depend on your point of view.
There have been many. Individual contenders would, perhaps, be;
Attila the Hun
Vlad the Impaler
Adolf Hitler
Pol Pot
There are also those that sanctioned terrible deeds but took no part in the acts themselves, to many these people are far worse. Some of whom are now revered.
adolph Hitler
Hitler was the worst person to ever walk the earth!
Justin Beiber!
it will vary by the person's opinion
Yes he is.
This is the worst website ever...
absolutely the worst person ever
It is different with each person. The one you hate most is your worst console.
Harry styles worst person is most prob himself ;3(or Maybe taylor Swift)
Neritic zone
The worst player is on Xbox Live his Gamertag is Nate State 14
you are the worst person I have ever seen