When a Master Chief (Old Nepleslian Rank) is appointed on a vessel, a tactical advisor is placed over him to help assure victory. This tactical advisor is known as a Senior Chief. The Senior Chief doesn't usually attend into battle, that's why representation and command is usually given to the Master Chief. However, the Senior Chief can override a Master Chiefs authority if he becomes out of hand, or makes too many wrong decisions. When there is more than one Master Chief (Old Nepleslian Rank), the Senior Chief assumes command and representation.

This rank has been discontinued. See Nepleslian Military Ranks.