From A Wiki of Ice and Fire
Khaleesi is a title that the Dothraki use to designate the wife of a khal, which is the leader of a khalasar. Due to the Dothraki bias against women, usually a khaleesi has less influence than the kos or bloodriders. If her husband dies before her, the khaleesi is taken to Vaes Dothrak, the holy city of the Dothraki people, to serve as a counselor for all khalasars as one of the dosh khaleen.
- Khaleesi Daenerys Targaryen