- "And in Astapor, the council you installed to rule over the city has been overthrown by a butcher named Cleon who's declared himself "His Imperial Majesty.""
- ―Jorah Mormont
Cleon was one of the thousands of slaves liberated after the Sack of Astapor. He isn't called "Cleon the butcher" because he is very violent, but because he used to work as an actual butcher of meat (though he is also very violent).
After the burning of the Meereen shipyards, Varys informs Tyrion Lannister, Grey Worm, and Missandei that the slave-masters have now retaken not only Yunkai but Astapor as well, leaving Meereen as the only part of Slaver's Bay that the slavers haven't reclaimed. Cleon's fate is unmentioned but he possibly died when his junta of vengeful freedmen at Astapor was defeated.
In the booksEdit
In the A Song of Ice and Fire novels, Cleon was once a slave owned by Grazdan mo Ullhor, serving as a butcher. It was said he could cut up a pig faster than any other man in Astapor. After gaining his freedom, Cleon stirs up the people of Astapor, claiming that the council is attempting to reinstate the deposed Good Masters. With the backing of the people, Cleon executes the council members and installs himself as king. At his command, every highborn boy in Astapor is seized to make new Unsullied for the trade. Daenerys ruefully notes that she didn't end slavery in Astapor: all that changed is that the old slaves are now the masters and the old masters are now the slaves.
He styles himself as "Cleon the Great", though he is often called "the Butcher King" (because he used to be a butcher). The TV series added the detail that he styles himself as "His Imperial Majesty" - thus while he proclaimed himself "King Cleon" in the books, it isn't clear if his official title is "Emperor Cleon" in the TV series.