Skullbreaker is an unlockable character within Call of Duty: WWII Nazi Zombies, he can be unlocked by completing a full challenge set in the map The Shadowed Throne, in this case being the "The Answer" challenge set.
- Crush Them Quick. - Responded to a bad situation swiftly and effectively ("Go Go Go!")
- Get to Wave 21 in under 25 minutes.
- Time Cruncher - Dismantled a machine of death and terror before nightfall. (Hard shutdown.)
- Fight Fair. - Ended the beast with determination and good training. (Some ground rules first.)
- Set The Stage - Taking too much enjoyment in this (Show time)
- Stay on the front of the Cabaret stage for 15 consecutive waves.
- Down The Sights - Cleared the area with deadly precision. (Target Practice)
- Finish 3 consecutive waves by only shooting or meleeing zombies in the head.