From The Stargate Omnipedia
Atlantis-based security officer. Walker was assigned to Major Lorne's team when a team was assembled to retrieve eggs from a nest belonging to the iratus bug species. He was killed in the initial attempt to infiltrate the nest. It is likely that at least one of the bugs began to feed on him before Lorne launched a grenade into the nest.
PLAYED BY -
FIRST APPEARED - Conversion
Conversion - Walker joins Major Lorne's team in an attempt to extract iratus bug eggs in the hopes of reverting Colonel Sheppard's transforming D.N.A.