Graverobber

Graverobber is an achievement in Halo Wars that is unlocked when you obtain all of the skulls.

Trivia

 * Possible reference to the "Grave Robber" Achievement in Call of Duty: World at War for finding all the death cards. Death cards also function extremely similarly to skulls; they make the game harder or easier to beat, and can add some interesting gameplay effects.
 * Although there are 17 skulls to obtain, the skulls for the Elite Honor Guard Wraith, and for the Flame Decal Warthog do not count towards the achievement.