From lace to sleeves, here's a look at all the ways the royal brides' gowns echoed one another's -- and the many ways in which they were totally unique.
As Meghan Markle tied the knot with Prince Henry at the star-studded royal wedding on Saturday, the stunning bride was resplendent in an elegant, pure white Givenchy gown that made her look every bit as regal as the newly-named Duchess of Sussex could have hoped.
While the top-secret style was unique to Meghan among other royal brides, there were still many aspects of her gorgeous gown that echoed the wedding dresses worn by Kate Middleton and Princess Diana.
ET's resident royal family expert Katie Nicholl -- author of Harry: Life, Loss, and Love -- tells ET that the nearly 16-foot veil that Meghan wore, which trailed behind her as she walked through St. George's Chapel at Windsor Castle, was "perhaps a nod to Diana."
"Because of course Diana had that wonderful train," Nicholl explained, referring to the Princess of Wales' 25-foot wedding dress train when she married Prince Charles in 1981. "That image of Meghan as she came down the steps with the veil trailing behind her, for me, was very reminiscent of Diana."
It was also rumored that Meghan would be wearing a tiara belonging to the late Princess Di. However, the actress opted to wear a different tiara, lent to her by her grandmother-in-law, Queen Elizabeth II -- a tradition followed by both Diana and Kate before her.
"The tiara she actually wore I thought was perfect with the dress," Nicholl said. "It was the Queen Mary's diamond bandeau tiara. Which actually, we have not seen before."
"It was tucked away in Her Majesty’s vault, which Meghan was given access to. And with the queens blessing, she chose to wear that tiara," Nicholl added. "I think it was, again, obviously a huge diamond. It can’t be understated. But for me, it was very simple and very elegant."
Looking back at Kate and Diana's very beautiful and very different wedding gowns, it's clear how challenging it was for Meghan when deciding on a dress that would be traditional, elegant and all her own.
"Meghan was in quite a difficult position, because she was never going to go down the line with anything that was too similar to Kate's dress," Nicholl explained. "All of that lace. That sweetheart neckline. Kate did that. That was Kate's dress."
"And she certainly wasn’t going to be copying Diana’s dress," she added. "I think she was very clever to come up with something that was bold, was simple, [and] was different."
When Diana walked down the aisle at St. Paul's Cathedral in London on July 29, 1981, the then-20-year-old bride wowed the world in a dress by Elizabeth and David Emanuel. The iconic, voluminous dress incorporated ivory silk taffeta, antique lace, sequins and over 10,000 pearls. Diana's veil alone required over 153 yards of tulle to create.
The gown specifically featured antique, hand-made Carrickmacross lace, which had once belonged to Queen Mary. It's possible that Meghan's selection of Queen Mary's diamond bandeau tiara could have been a very subtle tribute to Diana's use of Mary's Carrickmacross lace.
Following their wedding, Diana's dress became one of the most iconic fashion moments of all time.
When Kate and Prince William exchanged vows at Westminster Abbey in London on April 29, 2011, the then-29-year-old blushing bride looked absolutely amazing in a dress designed by Sarah Burton, the creative director of Alexander McQueen.
The dress predominantly featured French Chantilly lace and English Cluny lace throughout the bodice, skirt and underskirt, as well as the sleeves. The back of of dress was finished with 58 gazar and organza covered buttons fastened by Rouleau loops.
Meanwhile, Kate's skirt -- which was made of white and ivory gazar -- was designed to evoke the idea of a blossoming flower. Padded around the hips, the skirt flowed out to the floor and out to a comparably minimal nine-foot train.
Finally, for Meghan's dress, the 36-year-old actress turned to Clare Waight Keller, the artistic director of Givenchy -- the fashion house famed for their collaboration with movie star Aubrey Hepburn in classic films like Breakfast at Tiffany's, Sabrina, Funny Face, How to Steal a Million and Charade, among others.
The gown's immediate focus is the bateau neckline, which was chosen to gracefully frame Meghan's slender shoulders and emphasis her sculpted waistline. The pure white dress also featured slim, three-quarters sleeves and a train that flowed in soft round folds cushioned by an underskirt in triple silk organza.
While the three brides' dresses were all very different, all three also incorporated some notable similarities -- including the level of secrecy surrounding their creation. The designers of all three gowns were kept a tightly guarded secret until the big day.
All three brides wore tiaras -- which were borrowed from Queen Elizabeth -- and all three styled their veils in a similar manner.
Additionally, Kate, Diana and Meghan all incorporated lace into their looks in different ways and all three brides wore sleeves, maintaining a traditional look respectful of the regal occasion.
For more on Meghan's gorgeous Givenchy gown, check out the video below.
Additional reporting by Marisa Runyon.