Announcer

The announcer is a minor character in Portal 2. The announcer is known by his rigid masculine sound line. His voice actor is Joe Micheals. The Announcer seems to be taking over the lab, and fulfilling the basic needs for the lab to keep running before Portal 2. In Portal 2, The announcer guides Chell through Test chambers with pre-recorded messages.

He is an AI system designed to work in extreme and low power conditions to keep research and testing going, even during "circumstances of potentially apocalyptic significance” so “science can still be done.” Although, unlike many robots and AI in Aperture such as GLaDOS, Cores, or even Turrets, the Announcer does not have a physical presence and displays no hints of sentience. Instead, he rather is or is a part of the basic system of Aperture, his lines similar to computer alerts and triggered in the same fashion (such as deleting a file, indicating problems with the reactor core, etc.) He shows no acknowledgement to the outside the facility, no ability to record results from a test, no recognition of Chell being the one who, no desire to change tests within the facility or create new inventions, or ability to realize that the faulty turret used to sabotage the turret production line was flawed. He can, however, read files, detect life and the overall condition of the facility, operate the sprinkler system, as well as override the main AI in situations like stalemate procedures.

Indicated by his presence behind the scenes of Aperture especially concerning the production of Turrets, the Announcer maintains many ancillary functions that the main AI doesn't overlook but can utilize, and continues to make sure that minuscule problems are taken care of and that the main AI knows of any major problems occurring within Aperture.

Trivia

 * Several unused voice lines indicate that at some point during development of Portal 2, the Announcer's job was to be filled by GLaDOS herself, before ultimately being replaced by Joe Micheals' rendition of the script.