Headhunter Achievement in Halo: The Master Chief Collection

In total, there are 13 skulls scattered across each of the 10 missions in the Campaign that must be collected for this achievement. These skull collectibles are extremely well-hidden and come in the appearance of an actual human skull. At times, you will find that some are only obtainable for reaching obscure locations via grenade jumps and other advanced tactics. Needless to say, it will take a tremendous amount of exploring to locate these skulls.

These skulls are a unique collectible in that they act as significant gameplay modifiers. When activated via the Campaign Lobby Menu, skulls will alter the way the Campaign is played by either removing your HUD, granting infinite ammo and grenades, or even disabling the recharge ability of your shields unless you melee an enemy. With that said, these skulls are an awesome set of collectibles to hunt down. Take note however skulls will not appear while playing in Classic Mode. Once all 13 skulls have been collected, this achievement will unlock.