But there's one famous former royal member who won't be running to the mailbox.
So who is it?
Turns out that Sarah Ferguson, The Duchess of York, will not be attending the April 29th festivities, and apparently never planned on being included, People reports.
"She will not be attending. She never expected to be invited," a spokesman says.
Her rep says that Fergie will be overseas during that time, but her side of the family will still be represented at the nuptials.
The 51-year-old's daughters, Princess Beatrice, 22, and Princess Eugenie, 20, are expected to attend.
And it seems Fergie has learned her lesson from the days when she tried to sell access to her ex hubby, Prince Andrew, for cash to an undercover reporter.
"She has declined all commercial work relating to the wedding," the spokesman says, and refuses all offers connected to the wedding despite being constantly contacted by media around the world.
The Duchess has instead been working on a special documentary for OWN, Oprah Winfrey's new network. It is scheduled to air later this year.