Walter is one of Chandler's co-workers. He briefly appears in "The One Where Emma Cries" portrayed by Michael Kurtz (uncredited).
During a business meeting at his job, Chandler is very tired and almost falls asleep. Walter is the colleague seating to his left side, and Chandler dozes off towards Walter.
The actor Michael Kurtz playing Walter doesn't say a line in the episode and is not credited.