Tower Of Knowledge

I am struggling with the following definitions:

• An expert whose knowledge/wisdom concerning a certain problem set is not shared with other team members.

• A person in whom rests a detailed and actionable collection of information that
  • no other team member possesses
  • other team members may know a little of this, but cannot sufficiently act on what they know

This person is also well described, as a team of one, by the TruckFactor