Halo: Campaign Evolved includes hidden Skulls, optional collectible modifiers that alter gameplay or add extra challenges. Finding them matters for players seeking to customise campaign runs, unlock achievements, or complete the game fully.

The article is presented as a location guide for every Skull, likely organising each collectible by mission or area and explaining where to find it. However, the supplied article text contains only a JavaScript prompt, so it provides no verifiable locations, numbers, or specific gameplay details.