despot
Concise Oxford English Dictionary © 2008 Oxford University Press:
despot /ˈdɛspɒt/
▶noun a ruler who exercises absolute power, especially in a cruel or oppressive way.
– derivatives
despotic adjective,
despotically adverb,
despotism noun.
despotic adjective,
despotically adverb,
despotism noun.
– origin C16: from Fr. despote, via med. L. from Gk despotēs ‘master, absolute ruler’.
'despot' also found in these Oxford entries:

