Grunt is a genetically engineered Krogan super soldier. Bred and educated in a tank, he was intended to exemplify the best traits of the krogan, and help reinvigorate his species. In the meantime, he fights alongside with allied friends to satisfy his natural desire for violence.
Grunt was created on Korlus by the krogan warlord Okeer, who was originally investigating the genophage. However, Okeer gradually became obsessed with his work and realised that surviving the genophage had become the only benchmark for a good krogan, which was weakening the species as a whole. He decided to produce a genetically pure, superior krogan—a super soldier—and poured all his efforts into his experiments, even seeking help from the Collectors. After rejecting thousands of specimens as unworthy, Okeer finally produced his perfect prototype before he died from toxins released by Jedore, a Blue Suns mercenary. Commander Shepard, who had come to Korlus hoping to recruit Okeer, instead, recovered the super soldier's tank and took it aboard the Normandy SR-2.