Pono

Pono is an unseen character in Game of Thrones. He is a Dothraki Khal.

Season 1
After discovering the severed head of Rakharo inside a bag carried by Rakharo's horse, Ser Jorah Mormont considers either Khal Pono or Jhaqo as the culprits and that Rakharo was killed as a demonstration of contempt for the notion of a female leading a Khalassar.

In the books
In the Song of Ice and Fire novels, Pono is a ko in Khal Drogo's khalassar. After Drogo's fall from his horse and subsequent incapacitacion, Pono is one the first of several kos that declares himself Khal and takes a portion of the khalassar as his own.