From Halopedia, the Halo wiki
Former computer science teacher to Evelyn Rousseau
Mr. Garbett was a human school teacher who taught Evelyn Rousseau computer science.
In 2548, Mr. Garbett taught Evelyn Rousseau computer science where he gave her extra credit work. However, according to Evelynns father Mikal Rousseau, Garbett didn't challenge her enough.