The Unarmed Marine is a hidden Easter egg on the level 343 Guilty Spark. His character model is that of a standard Marine. It appears that SPV3 wanted his model to load before the cutscene that he later appears in; they thus coded him to load early in the level, and simply used the area outside of the level as a storage area. He can be shot and killed, just like any other Marine.
To find him, you must stay inside the Pelican that drops you off at the beginning of the level; to do this, throw a grenade as soon as you are able to. Stay inside the dropship as it flies off. After it travels a certain distance, the Pelican will land you off outside of the level barriers. By exploring around, you will eventually come across the Marine.
- In Halo CE, the Hidden Marine uses the model of Private Mendoza. However, since all the Marines are identical in SPV3 (with the exception of Avery Johnson) the Hidden Marine uses the standard model.