Are there any new "characters" I should know about?
Yes, the big newbie teased for Season 3 is Camilla (née Camilla Rosemary Shand), who goes on to become Prince Charles' second wife and the Duchess of Cornwall. Fittingly, she'll make her debut alongside a more mature Prince Charles and Princess Anne. The first of the trio to join the ensemble cast was Josh O'Connor (Florence Foster Jenkins), who'll be portraying Princes Charles for the next two seasons. O'Connor replaces Julian Baring in the role, and of his casting, he told THR, "I am thrilled to be joining The Firm for the next installment of The Crown … Seasons 3 and 4 will follow some of the most turbulent events in the Prince of Wales' life and our national story, and I'm excited to be bringing to life the man in the midst of it all. I'm very aware it's a formidably talented family to be joining but reliably informed I have the ears for the part and will fit right in."
Opposite O'Connor will be Emerald Fennell of Call the Midwife as Camilla Parker Bowels, and interestingly enough, her former Call the Midwife co-star Erin Doherty will play Princess Anne. On playing Camilla, Fennell said, "I'm absolutely over the moon, and completely terrified, to be joining so many hugely talented people on The Crown … I absolutely love Camilla, and am very grateful that my teenage years have well prepared me for playing a chain-smoking serial snogger with a pudding bowl hair cut."
As for other castings, Marion Bailey is replacing Victoria Hamilton in the portrayal of Queen Mother, and Gillian Anderson is taking on the Iron Lady, the former British Prime Minister Margaret Thatcher, for the next two seasons.
Another interesting, highly anticipated casting announcement came in April 2019 when THR reported newcomer Emma Corrin will play Charles' first wife, Princess Diana of Wales -- a casting that is apparently so spot-on the actress told THR she was offered the part immediately during her audition. Don't get too excited to see her story unfold quite yet, though, because Corrin won't be stepping into the cast officially until Season 4. It was always planned for Princess Di to arrive further into the series, as she reportedly didn't meet Charles until about 1977, which expands beyond the timeline of Season 3. Of her casting, though, Peter Morgan said in a statement to THR, "Emma is a brilliant talent who immediately captivated us when she came in for the part of Diana Spencer. As well as having the innocence and beauty of a young Diana, she also has, in abundance, the range and complexity to portray an extraordinary woman who went from anonymous teenager to becoming the most iconic woman of her generation.”