Halo: Campaign Evolved has 42 total Skulls available.
Skulls are gameplay modifiers that alter the campaign rather than ordinary collectibles that simply unlock lore. They can make combat harder, add unusual effects, change weapon behavior, or otherwise remix a mission. This gives the remake a substantial replayability layer beyond its story campaign.
The total includes 39 Skulls discovered as collectibles across the campaign’s 13 missions. Three additional Skulls become available through the Campaign Remix feature, so the headline total is larger than the number physically found during normal mission exploration.
A common mix-up is answering 39 because that is the collectible count, or 26 because that is the number of returning legacy Skulls. The full total is 42: 26 returning Skulls plus 16 new ones. Campaign Remix is therefore part of the count, not an unrelated bonus mode.