The most despicable name in the sight of Allah is that of a man named the King of kings. There is no king but Allah

The Messenger (may Allah's peace and blessings be upon him) informs us in this Hadīth that the most despicable and meanest of people in the sight of Allah, the Almighty, is someone who has a name that projects meanings of glorification and pride that befit none but Allah, the Exalted, such as the King of kings. This signifies rivalry with Allah. A person called by such a name claims to be or is claimed to be a rival to Allah, the Almighty.

Therefore, he is regarded as the most despicable and most malicious person in the sight of Allah or it is probably meant that he is one of the most hated of people. The Prophet (may Allah's peace and blessings be upon him) makes it clear that there is no true King for this universe, including all its rulers and ruled, but the Almighty Allah.

It is hoped this Hadīth will be a reminder to those who call people by certain names or titles without considering their meanings and implications, lest they would be subject to the evil consequence this Hadīth warns against. May Allah help all of us!