Melbourne-born software engineer Oliver Mulherin has lived most of his life outside the public eye – until he quietly married Sam Altman, the CEO of OpenAI – the company behind ChatGPT and one of the most powerful figures in global tech.
‘We would not be making this pledge if it weren’t for the hard work, brilliance, generosity, and dedication to improving the world of many people that built the scaffolding of society that let us get here,’ the couple wrote in their Giving Pledge letter.
‘There is nothing we can do except feel immense gratitude and commit to pay it forward and do what we can to build the scaffolding up a little higher.’
Aussie born Mr Mulherin first entered the public spotlight in 2023, when he and Mr Altman attended a White House state dinner hosted by President Joe Biden in honour of Indian Prime Minister Narendra Modi.
The couple married in a private ceremony in Hawaii in early 2024, and in February 2025, they welcomed their first child via surrogacy.
‘Welcome to the world, little guy,’ Mr Altman posted on social media on February 22, alongside a close-up of the newborn’s hand gripping an adult’s finger.
‘He came early and is going to be in the NICU for a while. He is doing well, and it’s really nice to be in a little bubble taking care of him. I have never felt such love.’
Mr Mulherin attended the prestigious John Monash Science School before graduating from the University of Melbourne in 2016 with a degree in computer science.
His career has taken him from Melbourne’s tech scene to Silicon Valley, with roles at Meta, Broadwing, and SPARK Neuro, working on projects ranging from AI-powered language tools to video games.
It’s still unclear how Mr Mulherin and Mr Altman first met, but both were working in the Silicon Valley tech scene at the time – specialising in artificial intelligence.
Mr Altman’s fortunes began when he sold his social-mapping company Loopt for million $42 million in 2012.
Using that money, Mr Altman started his own venture capital investment fund.
After a stint as the CEO of the startup accelerator Y Combinator, Mr Altman was hired as CEO of OpenAI in 2019.
At the time, OpenAI was already worth $123.8billion, but that value has now risen to an estimated $464billion.
Mr Altman came out as gay during high school, a surprise to his mother who had seen him as ‘unisexual and techy.’
Mr Altman’s marriage to Mulherin comes after the OpenAI CEO endured a turbulent period in November 2023, when he was dramatically ousted from the company and poached by Microsoft.
Following the announcement, ex-Twitch boss Emmett Shear was named as interim chief executive, sparking a staff mutiny that led to ‘intense discussions’ among bosses.
This resulted in Altman’s re-appointment as CEO of OpenAI less than a week after his unexpected departure.
Now based in San Francisco, the couple divide their time between the city and their sprawling 950-acre Napa Valley estate, Green Valley Ranch, purchased in 2020 for $24.5million USD, well below its $40million USD asking price.
The property, previously owned by a group of eight men for more than 40 years, features vineyards producing wine grapes and herds of beef cattle cared for by farmhands, despite Altman being a vegetarian.
Earlier this year, Mr Altman also purchased three adjacent homes in San Francisco for nearly $20 million each, adding to his property portfolio, which includes a historic six-bedroom, seven-bathroom Russian Hill mansion bought in 2020 for AUD $42 million.
That mansion is now at the centre of a bitter legal battle with developer Greg Malin and his company Troon Pacific.
Mr Altman claims the home is ‘plagued by shoddy construction’ and alleges he was misled during the purchase.
Estimated repairs are around $6million, with the dispute still before the courts.
Mr Altman is also facing a separate legal challenge from his sister, Ann Altman, who in January 2025 filed a lawsuit in Missouri alleging he sexually abused her as a child between 1997 and 2006.
Ann Altman, 30, filed a complaint January in a US District Court in Missouri – where the siblings grew up – that alleged her brother molested her between the years of 1997 – when Ann was just three years old and Sam was 12 – and 2006.
Ann Altman claimed that because of this alleged abuse, she ‘suffered a loss of enjoyment of a normal life as a consequence of her emotional injuries.’
She is seeking $75,000 in legal fees and unspecified damages from a jury trial, per the complaint.
Mr Altman posted a statement to social media that credited not just to himself but his mother Connie and brothers Max and Jack denying the allegations.
‘Annie has made deeply hurtful and entirely untrue claims about our family, and especially Sam. We’ve chosen not to respond publicly, out of respect for her privacy and our own. However, she has now taken legal action against Sam, and we feel we have no choice but to address this,’ they wrote.
They added that Annie ‘faces mental health challenges’ and they have helped her financially – including promising to buy her a home and pay her rent and medical expenses – but said she ‘continues to demand more money from us.’
Ann has, according to Sam, his brothers, and mother, made increasingly extreme allegations against her family over the years, leading up to this lawsuit.
Those allegations included withholding her share of their late father Jerry’s 401k funds, hacking her WiFi and shadowbanning her from various social media outlets.
‘All of these claims are utterly untrue. This situation causes immense pain to our entire family. It is especially gut-wrenching when she refuses conventional treatment and lashes out at family members who are genuinely trying to help.’
Missouri state law has a statute of limitations for child sexual abuse claims until the alleged victim is 31 years old.
Ann and her brothers have had their difficult, estranged relationship documented before, in a 2023 New York Magazine profile.
Writer Elizabeth Weil said that Annie ‘does not exist in Sam’s public life’ and goes through her various mental health struggles, including claims that she wanted to commit suicide at age six.
In 2020, she relocated to Hawaii and in recent years has financially supported herself by doing sex work, including an OnlyFans site.
‘As Annie tells her life story, she felt special and loved when, as a child, Sam read her bedtime stories. Now those memories feel like abuse,’ the newspaper profile claimed.
The story also said that Sam Altman has wanted to buy her a house and the family said in a statement: ‘We love Annie and will continue our best efforts to support and protect her, as any family would.’