From Halopedia, the Halo wiki
|Political and military information|
Gratney was a human scientist. Along with Walis, Gratney developed the Gratney-Walis Hierarchical Aptitude Score, a score used at Unified Combined Military Boot Camp to evaluate a recruit's command potential.
List of appearances
- Halo: Evolutions - Essential Tales of the Halo Universe
- The Impossible Life and the Possible Death of Preston J. Cole (First mentioned)