The 30-year-old Girls actress stopped by Andy Cohen's SiriusXM radio show, Radio Andy, earlier this week and dished about where the comparisons between her and Kate Middleton -- who celebrates her 37th birthday on Wednesday -- originated.
The idea struck after Williams began getting told "once or twice a week" that she looked like the Duchess of Cambridge, something the actress definitely took as a compliment.
"I think it was just that I was white with brown hair and seemed slightly regal in some way, which is a huge compliment," she said. "She's my dream person. She's so elegant! I would faint in her presence."
Williams was again compared to the royal when fans noticed that her wedding gown resembled the Duchess' Alexander McQueen dress from her nuptials. For Middleton's April 2011 wedding to Prince William, she donned a long-sleeve gown with lace details and an elegant train.
When it came time for Williams to tie the knot to Ricky Van Veen in September 2015, she also opted for a long-sleeve dress. Williams insisted, though, that any similarities between the two gowns was merely a coincidence.
"I'm sure that's what an article said it's inspired by -- like, I can just picture that in print -- it's not the case," she said. "But it also had long sleeves."
Williams joked, "Then I guess it was just 100% just stolen from her. I stole Kate Middleton's wedding gown."
While on Radio Andy, Williams also discussed the show for which she's most well known -- Girls. The HBO series, created by Lena Dunham, came to an end in 2017, but Williams is all for a reprising her character, Marnie Michaels.
"I hope for one. It'd be so fun. Likelihood? I genuinely don't know. I have no idea. It'd be so much fun," she said. "I think it would need to be, like, every decade. At one point Lena said, 'Every decade I want to check in on them.' I think that would be really, really fun."