Garrosh Hellscream was born on the orcish homeworld of Draenor, and grew up untainted by the demonic blood that twisted the orcs who invaded Azeroth. Though he wasn't demonically influenced himself, Garrosh was haunted by his family's legacy: his father, Grommash Hellscream, was the first orc to embrace corruption by drinking the blood of the pit lord Mannoroth. Garrosh lived in the shadow of his father's acts until he met Warchief Thrall, founder of the renewed Horde, who explained to the younger Hellscream how Grommash ultimately gave his life to lift the demonic blood-curse, and freed his race from servitude to dark forces.
Uplifted, Garrosh joined Thrall in Azeroth and quickly became a hero of the Horde by leading a successful offensive against the Lich King. When Deathwing shattered the world, Thrall was forced to leave his throne to stop the destruction, and left Garrosh as his successor. Looking for ways to gather more resources and new territory for his people, Hellscream has initiated several brutal strikes against the Alliance, razing Jaina's city of Theramore and later clashing over the continent of Pandaria. As warchief, Garrosh's controversial actions - among them claiming the heart of an Old God and ravaging Pandaria's Vale of Eternal Blossoms - fueled rebellion, leading Horde dissidents and a vengeful Alliance to besiege Orgrimmar and depose him.
Victorious, Orgrimmar’s liberators dragged Hellscream to trial in Pandaria, where they recounted each of his crimes against Azeroth. The former warchief was unapologetic; worse, he escaped his captors, vanishing with the aid of the bronze dragon Kairozdormu to an alternate Draenor in the past. There, he was able to confront Gul'dan and witness his transformation into one of the first green orcs, corrupted by the influence of the fel powers, and slowly change the course of events leading to the birth of the Iron Horde. Garrosh also managed to give an idea to create a gateway between the alternate timeline and the current one in order to return to exact his vengeance on Azeroth, in a form of the Iron Horde's Dark Portal and then sent the Iron Horde in order to conquer the world. During this conflict he was eventually defeated and killed by Thrall in a mak'gora.