We asked, but no reader gave this answer: Penny Johnson Jerald has been named the new captain on Castle.
The actress has guest-starred on Bones and NCIS and is best known for playing 24 villain Sherry Palmer over the first few seasons of that series.
As first reported by Michael Ausiello, Jerald will portray Victoria "Iron" Gates, a strict, former Internal Affairs investigator. Look for her to immediately clash with a certain author/quasi detective.
Jerald is coming on board because Ruben Santiago-Hudson's Captain Roy Montgomery was killed off on the season three finale.