An autocrat is a monarch with the powers of a dictator.
An autocrat is a self-appointed ruler, nowadays this equates to a despot of a dictator. The best example of a true autocrat is Nicholas II, who was the last Tsar of Russia until overthrown by the...
Dictator,czar,and emperor are each a type of autocrat.
"despot" and "tyrant"
A ruler with unlimited authority