|Function(s) / Belongings|
|Rank / Occupation|
|Chronological and political information|
 Half-Life: Opposing Force
Walter is first introduced in the chapter Vicarious Reality, in a hologram message intended for him, in Sector E. In that message, a colleague explains to him that they were finally able to successfully detach a Barnacle from its point of gestation, but that they were still only able to coerce the creature into latching onto organic materials. The scientist then states he has to cease his experiments on the creature because the Administrator has called him down to the Anomalous Materials lab for an important experiment, and that Bennet should take on the work on specimen 1176. After listening to that message, Adrian Shephard takes possession of specimen 1176, the Barnacle Grapple, stored in a nearby room.
 Half-Life: Blue Shift
In Blue Shift, it is learned that when the Resonance Cascade occurred at Black Mesa, Rosenberg and a colleague named Harold formulated a plan of escape: They would reach the disused Prototype Labs and use its old teleport to teleport themselves to the surface and escape. Along with Simmons and Bennet, they set out to accomplish this, but they do not count on the arrival of the HECU and their immediate hostility. Harold is killed and Rosenberg is captured, but Walter and Simmons escape unscathed to the Prototype Labs and get it ready for the teleportation sequence.
When Rosenberg returns with a security guard named Barney Calhoun, Walter is extremely relieved and briefs him on the situation. After the teleport is set up with the help of Barney, Walter is the first one to go through, and arrives outside the Black Mesa South Access Tunnel. Simmons soon comes through as well, and gets a Black Mesa SUV ready for their escape while Walter uses a crowbar to open a gate. Soon, Calhoun and Rosenberg teleport nearby, and they escape with the SUV. As with Rosenberg and Simmons, Bennet's fate afterwards remains unknown.
 Behind the scenes
- Walter's name is a nod to Walter's World (archived version), a popular fan fiction set in the Half-Life universe created by Kevin "Fragmaster" Bowen on Planet Half-Life. The popularity of the feature eventually lead to a reference in Opposing Force as well as the introduction of the character in Blue Shift. "Walter" also became the name of the generic "Scientist 01" face texture name in the High Definition Pack.
- The spelling of his surname can be seen in the Half-Life PlayStation 2 instruction manual, in the Hazard Course Training schedule.
 List of appearances
- Half-Life PlayStation 2 instruction manual
- Half-Life: Opposing Force (First appearance) (Mentioned only)
- Half-Life: Blue Shift