The actress' daughter, Matilda Ledger, was only 2 years old when the child's father, Heath Ledger, died of an accidental drug overdose on Jan. 22, 2008.
Ledger was 27. The movie he would posthumously win an Oscar for the following year, The Dark Knight, was still months away from its theatrical release, and eventually a trio of actors were enlisted to fill the void in Terry Gilliam's then-unfinished The Imaginarium of Doctor Parnassus.
But while Hollywood was devastated by the senseless loss, and people started to dig into the destructive lifestyle Ledger was leading in the months leading up to his death, it was the loved ones left behind whose lives changed forever.
Heath and Michelle had fallen in love on the set of Brokeback Mountain, for which both scored their first Oscar nominations—and they couldn't have looked more in love as they navigated, first, the film's festival circuit, and then the 2006 award season together.
Williams, in particular, was positively radiant—not least because they were in the midst of becoming a family of three at the time—and every chance she got she talked about how proud she was of Ledger's performance.
"It's just deserved," she told E! News in December 2005, two months after she and Ledger had become parents. "It's sort of obvious after you see what he does. I forgot he was my boyfriend when I was watching it, I really did." And he was equally congratulatory, saying about Williams, "She's a phenomenal actress. It's boring to say she's at a turning point—she's always been turning a corner and she'll continue to turn corners.
"She's incredibly talented and beautiful, and her performance in this movie is incredibly controlled and deep, and full of emotion. I'm incredibly proud of her."
"We started promoting the movie about three weeks after she was born, which was too soon," Williams said on The Oprah Winfrey Show in January 2006 during an appearance with Ledger and their Brokeback co-stars Jake Gyllenhaal and Anne Hathaway. "I'm just learning lessons now, like learning how to be a working mom."
Asked about Williams and Ledger's on set romance, Gyllenhaal recalled the trailer count going from four to three, and Hathaway said, "There were sparks immediately. It was adorable."
As for Ledger, he called Williams the "perfect mom" and said, "I'm so proud. I just fall deeper and deeper in love with both my girls."
There were frequent sightings of the family of three in their Brooklyn neighborhood, and fans were able to see that Williams wasn't kidding when she told Oprah that Matilda looked like her dad.
But in September 2007, the news broke that Heath and Michelle had split up. "It was rocky for awhile," a source told People at the time. "They did what they could to make it work." Only in hindsight would it become apparent that Legder's demons had started to get the better of him.
After his death, Williams said in a statement: "Please respect our need to grieve privately. My heart is broken.
"I am the mother of the most tender-hearted, high-spirited, beautiful little girl who is the spitting image of her father. All that I can cling to is his presence inside her that reveals itself every day.
"His family and I watch Matilda as she whispers to trees, hugs animals, and takes steps two at a time, and we know that he is with us still. She will be brought up in the best memories of him."
Williams gathered with Ledger's family for a memorial in his native Australia and otherwise grieved as someone who was still very much in love with Heath when he died. It wasn't difficult to imagine that she would never have broken up with him in the first place if his issues hadn't put their relationship in dire straits—and that hopes of a reconciliation were still on the table.
In 2010, she would talk about immersing herself in loss after reading Joan Didion's memoir of grief written after the sudden death of her husband, The Year of Magical Thinking, and how feeling better was also a strange beast to confront.
"In a strange way I miss that year—because of all those possibilities that existed then are gone," Williams said on Nightline in her first TV interview after Ledger's death. "It didn't seem unlikely to me that he could walk through a door or could appear from behind a bush, it was a year of very magical thinking. In some ways I'm sad to be moving further and further away from it."
But first and foremost, Michelle had a child to raise—as a working mom, a single mom and, perhaps just as trickily, as a famous mom.
Though his films, of which Ledger made enough to suit any movie-watching mood, gave him cinematic immortality, it's Matilda who remains the human embodiment of Ledger's legacy. So Williams quickly had to get used to interest in her and her daughter increasing by a hundred-fold.
And somehow, she has since managed to give Matilda a quiet, private life, while simultaneously cementing her own reputation as one of the finest actresses of her generation and having an enviable career as a star of film and theater and the face of luxury brands like Louis Vuitton and Band of Outsiders.
Taking a break from the spotlight and getting Matilda out of the city certainly helped in those early days.
"We moved—we left Brooklyn and lived in the country for six years because it was an intolerable state of existence," Michelle told the New York Post last June. Williams had to navigate the usual big-city gauntlet for work, but her habit of choosing only the projects that called to her certainly served her well.
"I wish I was more of a go-getter," the Montana native told the paper. "I just sort of sit and wait for things to come my way."
Only in 2014 did Williams sell the Boerum Hill townhouse that she and Ledger moved into together in 2005, reportedly getting $8.8 million—17 percent over ask—for the six-bedroom home. According to Curbed New York, she purchased a 114-year-old Colonial-style mansion—a $2.5 million, eight-bedroom fixer-upper—in Ditmas Park in 2015, and local real estate blogs have been hanging on every step of the renovation process.
And choosing the East Coast over the West Coast is still a smart move if you want to be relatively left alone. While the Big Apple, Brooklyn included, isn't exactly devoid of Hollywood-type activity, Los Angeles remains the heart of the biz—and all the pitfalls of fame that come with it.
Williams recently told Elle, "If you feel like people are watching you, it's impossible to have an authentic experience of being alive. There's a performative aspect and a guardedness, and that's just death. I don't know how to live like that, and I don't know how to give a life to my child like that."
She previously called Kristen Bell, who was instrumental in getting a number of media outlets to stop publishing unauthorized photos of celebrities' children, her "personal hero." (E! News was among the outlets that implemented the new protocol accordingly.)
"[The picture ban] has changed our lives," Williams gushed to the Post. "I email [Bell] once every couple of months and say, 'I owe you everything. My daughter's happiness is in your hands.' Talk about a go-getter!"
Go-getter or not, Williams won the Golden Globe for Best Actress, Musical or Comedy, in 2012 for her take on Marilyn Monroe in My Week With Marilyn and she's a lock to get her fourth Oscar nomination—for her role in Manchester by the Sea as a wife and mom who's still grieving a horrific tragedy but doing her best to move on with her life—when nominations are announced on Tuesday.
But while very much a Hollywood fixture when award season rolls around, Williams has also protected her now 11-year-old daughter by keeping a tight lid on her own private life.
Over the years, she's had serious yet low-key relationships with filmmaker Spike Jonze and Jason Segel that both proved too logistically difficult, and she most recently was linked in 2015 to novelist Jonathan Safran-Foer, who at least lives in Brooklyn.
"The timing was impossible. I thought falling in love again was the only thing that was going to save me from the pain," Williams told Vogue in 2009 after she and Jonze had split up. "This erroneous idea: It just makes things more complicated."