Musk, 52, and Zilis already share twins Strider and Azure, who were born in 2021, according to CBS News. The birth of the couple’s newest child was first reported by Bloomberg. The baby’s name has not been announced to the public.
According to USA Today, Musk has now fathered at least 12 children among three different women.
He has three children with Canadian singer Grimes, CBS News reported. Their first, named X Æ A-12, was born in March 2020; their second child, named Exa Dark Sideræl, was born in 2021, according to the news outlet. Their third child, named Techno Mechanicus, was born in 2023.
The billionaire and founder of SpaceX had six children with his ex-wife, Canadian author Justine Wilson, USA Today reported. Their first child died at 10 weeks from Sudden Infant Death Syndrome (SIDS). Wilson and Musk were married from 2000 to 2008, CBS News reported.
The couple later had twins, Griffin and Vivian, in 2004, according to the news outlet. They were followed by triplets in 2006 -- Kai, Saxon and Damian.
According to her LinkedIn page, Zilis, 38, joined Neuralink, which was founded by Musk, in 2017. The Yale graduate was an adviser to OpenAI from 2016 to 2019, and served on the company’s board from 2020 to 2023.
Photos: Elon Musk through the years Here are some memorable photos of SpaceX founder and CEO Elon Musk through the years. (Pascal Le Segretain/Getty Images)
Photos: Elon Musk through the years 2008: Tesla founder Elon Musk attends the launch party for the Tesla Roadster, the world's first highway-capable all electric car available in the United States, at the Tesla Flagship Store on May 1, 2008, in Los Angeles. (Vince Bucci/Getty Images)
Photos: Elon Musk through the years 2009: CEO Elon Musk (left) arrives at the Tesla UK launch on June 25, 2009, in London. (Gareth Cattermole/Getty Images for Tesla)
Photos: Elon Musk through the years 2010: Toyota CEO Akio Toyoda, Tesla Motors CEO Elon Musk and California Gov. Arnold Schwarzenegger laugh during a news conference at Tesla Motors headquarters May 20, 2010, in Palo Alto, California. (Justin Sullivan/Getty Images)
Photos: Elon Musk through the years 2011: Talulah Riley and Elon Musk attend the 2011 Orange British Academy Film Awards at the Royal Opera House on February 13, 2011, in London. (Ian Gavan/Getty Images)
Photos: Elon Musk through the years 2012: Director Bryn Mooser, executive producer Elon Musk, executive producer Olivia Wilde and director David Darg of the film "Baseball in the Time of Cholera" attend the "Help Wanted" Shorts Program during the 2012 Tribeca Film Festival at the AMC Lowes Village on April 21, 2012, in New York City. (Cindy Ord/Getty Images)
Photos: Elon Musk through the years 2013: CEO and CTO of SpaceX and CEO and Chief Product Architect of Tesla Motors Elon Musk participates in a discussion at the New York Times 2013 DealBook Conference in New York at the New York Times Building on November 12, 2013, in New York City. (Larry Busacca/Getty Images for The New York Times)
Photos: Elon Musk through the years 2014: Actress Talulah Riley (left) and CEO of Tesla Motors Elon Musk attend the 2014 Vanity Fair Oscar Party hosted by Graydon Carter on March 2, 2014, in West Hollywood, California. (Pascal Le Segretain/Getty Images)
Photos: Elon Musk through the years 2015: Tesla CEO Elon Musk speaks during an event to launch the new Tesla Model X Crossover SUV on September 29, 2015, in Fremont, California. (Justin Sullivan/Getty Images)
Photos: Elon Musk through the years 2016: Elon Musk and actress Kate Hudson attend the 2016 InStyle and Warner Bros. 73rd annual Golden Globe Awards Post-Party at the Beverly Hilton Hotel on January 10, 2016, in Beverly Hills, California. (Jason Merritt/Getty Images for InStyle)
Photos: Elon Musk through the years 2017: Maye Musk (left) and SpaceX CEO Elon Musk attend the 2017 Vanity Fair Oscar Party hosted by Graydon Carter at Wallis Annenberg Center for the Performing Arts on February 26, 2017, in Beverly Hills, California. (Pascal Le Segretain/Getty Images)
Photos: Elon Musk through the years 2018: Elon Musk and Grimes attend the Heavenly Bodies: Fashion & the Catholic Imagination Costume Institute Gala at the Metropolitan Museum of Art on May 7, 2018, in New York City. (Neilson Barnard/Getty Images)
Photos: Elon Musk through the years 2019: SpaceX Chief Engineer Elon Musk (right) speaks with NASA Administrator Jim Bridenstine (center) while viewing the OctaWeb, part of the Merlin engine used for the Falcon rockets, at the SpaceX Headquarters, Thursday, Oct. 10, 2019, in Hawthorne, California. (Aubrey Gemignani/NASA via Getty Images)
Photos: Elon Musk through the years 2020: SpaceX founder Elon Musk celebrates after the successful launch of the SpaceX Falcon 9 rocket with the manned Crew Dragon spacecraft at the Kennedy Space Center on May 30, 2020, in Cape Canaveral, Florida. (Joe Raedle/Getty Images)
Photos: Elon Musk through the years 2021: Tesla CEO Elon Musk and Armin Laschet, CDU Federal Chairman and Prime Minister of North Rhine-Westphalia, talk during a tour of the plant of the future foundry of the Tesla Gigafactory on August 13, 2021, in Grünheide near Berlin, Germany. (Patrick Pleul - Pool/Getty Images)