Private First-Class G. Haley was a marine trooper on the G.F.S. Tyr when it crash-landed on Aether during the events of Metroid Prime 2: Echoes. Haley was a guard near the crashed ship and helped set up a base of operations. He was part of Force One. The Trooper Log that Samus Aran reads when she finds him implies that Haley was more than a little insane near the end of his life; in it, Haley says he was afraid to sleep because he thought "they" would eat him. This also implies that he foresaw the Dark Splinter attack coming.
PFC M. Veroni was nearly shot by Haley on nightwatch; Veroni then spoke to a male doctor (either PFC X. Dorminguez or LCOR T. Huxley, the medical officer) about Haley "losing it." However, the doctor reminded Veroni that they needed all of the help that they could muster.
Haley's actions can be compared to Hudson from the film Aliens. A member of the Colonial Marines, he becomes quite scared of the Xenomorphs on Acheron LV-426, and loses his sanity. He is later killed by the very creatures he became petrified of.