Drogo is the leader of a Dothraki nomadic tribe.
Not much is known about about Khal Drogo's background except for the fact that he is one of the most powerful Dothraki warlords, commanding a khalasar of over 40,000 fearsome Dothraki.
In the first episode 'Winter is Coming' he is wed to Daenerys Targaryen after her brother, Viserys the rightful owner of the Iron Throne, makes a deal with Drogo. His sister's hand in marriage in return for an army. At the wedding he presents her with a horse as a wedding gift and they consummate the marriage later that night.
While on the way to Dothraki city of Vaes Dothrak, Daenerys tells him that she is pregnant with a baby boy.
After Viserys threatens the life of Daenerys and her unborn son, Rhaego, when demanding his army from the Khal. Drogo finally grants Viserys his 'golden crown.' He melts a golden belt in a cauldron and pours the molten gold over Viserys uncovered head, killing him in the process. Daenerys accepts his death coldly, calmly stating that Viserys wasn't a dragon as fire cannot kill a dragon.
In the wake of her brother's death, Daenerys continues to try and convince Khal Drogo to sail across the Narrow Sea and reclaim her kingdom. Robert Baratheon gives the order to have Daenerys assassinated. After a wine merchant fails in his attempt to poison her, Khal Drogo becomes enraged and vows to sail across the Narrow Sea and claim the Iron Throne for his unborn son.
As Drogo's khalasar pillages a village, Daenerys is shocked by their barbaric behavior. After seeing several of his men attempt to rape village woman, she orders them to stop, taking the woman as her own slaves. When one of his men questions Drogo about his Khaleesi's beheviour, Drogo sides with her, inciting the man. He fights Drogo but can only manage to cut Drogo's chest before Drogo cuts his throat and rips out his tongue. He receives treatment from Mirri Maz Duur at Daenerys request, despite rejections from Qotho.
Khal Drogo displays the typical Dothraki appearance of tanned skin with black eyes and hair. He is displayed as a quiet, graceful figure.
He is legendary among the Dothraki as being a fearsome warrior. He has never had his braid cut, a sign that he has never lost in battle.