Viola Davis portrayed Michelle Obama in Showtime's TV series, The First Lady
Viola Davis has become the 18th person to achieve the EGOT - winning an Emmy, Grammy, Oscar and Tony Award - as the Grammy Awards kick off in Los Angeles.
Davis completed her collection by winning best audio book for her autobiography Finding Me.
"I wrote this book to honour the six-year-old Viola," said the star. "To honour her life, her joy, her trauma, everything."
The star won the best supporting actress Oscar in 2016 for Fences.
Her Emmy Award recognised the TV drama How To Get Away With Murder, and she has two Tony Awards for her theatre work - featured actress in a play for King Hedley II (2001) and lead actress in a play for Fences (2010).
"I just EGOT!" announced the star on stage at the Grammys, becoming visibly emotional as she thanked her family for being "the best chapter in my book".
The 17 other EGOT winners include Sir John Gielgud, Rita Moreno, Andrew Lloyd Webber, John Legend and Jennifer Hudson.
Davis picked up her prize at the Grammys "premiere ceremony", which mostly recognises technical and genre categories.
Beyoncé has already won two prizes: Best dance recording for the song Break My Soul, and traditional R&B performance for Plastic Off The Sofa.
The awards bring her one step closer to becoming the most-awarded artist in Grammy history.
The star now has 30 trophies, just one short of equalling the current record holder, Hungarian-British conductor Georg Solti.
Harry Styles also picked up best engineered album for Harry's House, which is also up for the night's biggest prize - album of the year.
But the British star faces tough competition for that award, with Adele, Beyoncé and Latin star Bad Bunny among the other favourites.
Rock legend Ozzy Osbourne also won two awards, in the week he announced his retirement from touring.
His latest record, Patient Number Nine, was named best rock album, while the song Degradation Rules won best metal performance.
And British indie duo Wet Leg received two awards - including best alternative album and best alternative song for their breakout single, Chaise Longue.
"This is so funny," said singer-guitarist Rhian Teasdale. "What are we even doing here?"
Meanwhile composer and violinist Stephanie Economou received the first ever Grammy for best video game soundtrack, recognising her work on Assassin's Creed: Dawn Of Ragnarok.
The premiere ceremony is being hosted by YouTube star Randy Rainbow, who went viral during the Trump administration for videos that mixed political commentary with musical theatre numbers.
Taking to the stage at Los Angeles' Crypto,com Arena, he promised not to make cheap jokes about US Republican George Santos, who has admitted to making several false statements in his resume and biography.
"I will not even say his name," said Rainbow. "Even though he is nominated for best pop vocal album."
The main Grammys ceremony kicks off at Los Angeles' Crypto.com Arena on Sunday at 17:00 (local time) / Monday at 01:00 (GMT)
Comedian Trevor Noah is hosting for the third time, with performances due from Styles, Lizzo, Bad Bunny and Sam Smith.
But Noah has hinted that two pop megastars will also be gracing the stage.
"One of your favourite performers is a woman, and that woman is going to be performing at the Grammys," he said on the People's Every Day podcast this weekend.
"Then one of your other favourite performers is a man, and that man is going to be performing at the Grammys.
"And you're going, 'Oh, but that could be anyone.' But you know, it's not anyone, though, because you've been listening to their album the whole year and it's been huge."
