The controversial billionaire shared the news in his newly published biography and revealed that the baby’s name is Techno Mechanicus, Tau for short, on his social media platform, X previously known as Twitter.
The name is seemingly from the popular game Warhammer 40,000. Mechanicus is a word in the game associated with a group of cyborg warrior priests.
The mogul and musician, whose real name is Claire Boucher, often refer to their first two children as X and Y, in what appears to be a nod to Musk’s electric car models produced by electric car company, Tesla.
Tau Techno Mechanicus
— Elon Musk (@elonmusk) September 10, 2023
The pair, who are infamous for their fraught off-and-on relationship — the details of which they often share on X, tend to wait several months before announcing the birth of their children.
The couple reportedly separated last year and the age of their latest child has not been revealed.
The biography, titled Elon Musk, was written by American writer and journalist Walter Isaacson, who spent two years closely following the controversial and divisive billionaire.
The news comes shortly after Grimes took to the social media platform to call out Musk and Shivon Zilis, the mother of the mogul’s 22-month-old twins.
Replying to a post by Isaacson that included a picture of Musk with son X, Grimes wrote: “Tell Shivon to unblock me and tell Elon to let me see my son or plz respond to my lawyer.
“I have never been allowed to see a photo of these children until this moment, despite the situation utterly ripping my family apart.”
There was also a second picture of Musk, Zillis and their children Azure and Strider.
Grimes’ tweet has since been deleted.
Musk, who has been married three times, with two of the marriages to Westworld star Talulah Riley and the other to Canadian author Justine Wilson, is now father to 11 children.
He shares twins Vivian Jenna and Griffin, 19, and triplets Kai, Damian, and Sax, born in 2006, with Wilson. Their eldest son, Nevada, died at 10 weeks.
Vivian came out as transgender in June 2022 when she filed a request to change her surname to that of her mother’s and has spoken out about her dislike for her “transphobic” father.
Zilis welcomed her twins in November 2021, just one month before the arrival of Musk’s second child with Grimes via surrogate.