Actress Imelda Staunton - best known for her role as Professor Dolores Umbridge in the Harry Potter franchise - will step into predecessor Olivia Colman's shoes as Queen Elizabeth II in the final season.
"I have loved watching The Crown from the very start. As an actor it was a joy to see how both Claire Foy and Olivia Colman brought something special and unique to Peter Morgan's scripts," Staunton said on the casting decision.
"I am genuinely honoured to be joining such an exceptional creative team and to be taking The Crown to its conclusion."
It's interesting to note that the final season will end in 2003 meaning Prince Andrew's decision to step down amid the Jeffrey Epstein scandal will not make the script.
While the Duke and Duchess of Sussex are sure to be relieved that 'Megxit' will also escape the Netflix treatment.
The release date for season four has yet to be announced though we have been teased in recent weeks with sneak previews of what to expect as filming gets underway.
Emma Corrin will take on the role of Princess Diana in the next installment with Jack O'Connor returning as Prince Charles as their turbulent romance begins to play out.