Elon Musk and Sam Altman are headed to court. Meet the 9 players to watch.

World's richest man. Head of Tesla, SpaceX, and xAI. Right-wing megadonor and gadfly. Chainsaw-swinging grim reaper of DOGE.

Musk has held many titles. For the nine federal jurors being seated in Oakland in his civil case against Altman, three other titles will take priority: OpenAI investor, plaintiff, and testifying witness.

OpenAI used his millions in seed money to become a "market-paralyzing gorgon," Musk said in the lawsuit at the center of the trial. He's seeking $134 billion in compensation for OpenAI's and Microsoft's "unjust enrichment" on his dime.

Musk, who resigned from OpenAI in 2018, has been described as confident and combative in two previous turns on the witness stand, once in a securities fraud trial and again in a case that won him the reinstatement of his $55.8 billion Tesla pay package.

He's expected to spend two hours describing what he sees as his betrayed hopes for OpenAI's future.

Altman's lawyers say they plan to grill Musk for an additional four hours, asking him about "the promises he claims were made to him and his attacks on, and bid for, OpenAI in recent years."

Their lawyers also say they'll ask Musk about "his lack of communications with Microsoft" regarding his OpenAI investments. Altman's team is keen on defending OpenAI's licensing deal with Microsoft. and so will likely Musk about OpenAI's need, as it grew, for the vast amounts of cash and computing infrastructure that partnership provided.

Long known in tech circles as a Silicon Valley wunderkind, Altman skyrocketed to worldwide fame with the 2022 release of ChatGPT, now boasting 300 million weekly active users.

Losing to his former tech bro could cost OpenAI billions of dollars and upend how the company — one of the world's most valuable startups — operates.

Altman could be personally on the hook for any cash award, and Musk wants him ousted from OpenAI's nonprofit board and as CEO.

In taking the stand, Altman needs to convince jurors that Musk's investment in OpenAI had none of the strings attached that Musk claims. Altman also needs to convince jurors that OpenAI remains first and foremost a nonprofit — and that its for-profit arm remains dedicated to benefiting humanity.

Altman is expected to spend at least six hours on the witness stand, his time divided evenly between questioning by his lawyers and Musk's.

He'll be asked to give jurors a detailed description of OpenAI's founding and its partnership with Microsoft. He'll also be asked about Musk's contribution to — and bitter departure from —the company.

With years of experience in tech trials and keeping wealthy combatants in line, US District Court Judge Yvonne Gonzalez Rogers is an able referee for Musk v Altman.

In the two-year lead-up to trial, she has repeatedly kept the warring teams of lawyers in line. There will be no special treatment for billionaires in her courtroom. Musk and Altman must enter the courthouse through the public entrance — and they'll be footing the bill for the jurors' lunches during deliberations.

"You have plenty of money to pay for it," the judge noted during a hearing last month.

She didn't suffer gladly Musk's claims that his competing AI venture, xAI, has been "irreparably harmed" by the Altman-Microsoft partnership.

"I have billionaires versus billionaires," Gonzalez Rogers said at a hearing last year, calling Musk's "harm" claim "a stretch" and noting that he was still able to raise $11 billion in investments for xAI.

She has also credited Musk's lawsuit as worthy of trial, saying in a March 2025 ruling that, based on the evidence she's seen, his main claim — that Altman broke a contractual promise to keep OpenAI solely nonprofit — is a "toss up."

Microsoft's charismatic CEO, Satya Nadella, will be a key, though brief, witness in the trial.

Musk's lawsuit says both Microsoft and OpenAI — both are named as defendants — were "unjustly enriched" by their ongoing, six-year partnership

Explaining the partnership will take up much of Nadella's testimony.

Nadella is also set to tell jurors that he and Microsoft had no knowledge of any "duties" supposedly owed to Musk by virtue of Musk's OpenAI investments.

"Moreover, he will testify about Microsoft's support of OpenAI during Mr. Altman's November 2023 firing and subsequent rehiring," his lawyers say.

Avowed Altman loyalist Greg Brockman is an OpenAI cofounder, its former chief technology officer, and its current president. He's a defendant in the trial, too — and an important witness.

The AI pioneer will likely be asked about his private diaries, which include his musings about Musk's impending 2018 resignation. "This is the only chance we have to get out from Elon," he wrote at the time.

Other diary entries likely to pop up at trial show Brockman strategizing about increasing OpenAI's cash flow, and his own. "Financially what will take me to $1B?" he wondered.

Musk's side may use these entries to convince jurors that Brockman knew that pushing for profits would lead to, as his diary called it, "a very nasty fight."

"His story will correctly be that we weren't honest with him in the end about still wanting to do the for profit just without him," one key Brockman diary entry reads, referring to Musk.

It would be "morally bankrupt" to "steal" the company from Musk, he also wrote.

Musk, too, has a loyalist witness — AI investor and developer Shivon Zilis.

She's Musk's longtime collaborator, moving from Tesla to OpenAI, where they met in 2016, and then to xAI, where she helped with its 2023 founding. The two are co-parenting their four children.

A director at Neuralink, Musk's brain-computer interface venture, Zilis is also a plaintiff in the case.

She's expected to spend some three hours on the stand, with Musk's side questioning her about the founders' communications about OpenAI's early nonprofit mission.

Altman's side says they'll question her about her work and interactions with Musk during her time at OpenAI, and about "her actions as an OpenAI director."

The two appear to be on good terms, arriving hand-in-hand for a wedding at Mar-a-Lago in February.

OpenAI cofounder and now-former chief scientist Ilya Sutskever is widely recognized as a machine-learning prodigy.

The wild swings of his decadelong, on-and-off relationship with Altman may figure prominently in Sutskever's three hours of testimony.

At first, he was a dedicated colleague, rebuffing a $2 million retention offer from Google to join in OpenAI's 2015 founding.

Eight years later, he helped lead the mutiny that briefly ousted Altman from OpenAI. In a 52-page memo, he accused Altman of "a consistent pattern of lying" — only to quickly atone, joining a letter signed by 95% of OpenAI employees demanding Altman's reinstatement as CEO.

Sutskever resigned from OpenAI six months later to cofound a research lab, Safe Superintelligence, dedicated to fighting the risks of an AI-driven future — "the most important technical problem of our time," he said in announcing the venture.

Clues to whether Sutskever remains an ally or foe of Altman lie in his October 2025 trial deposition, in which he said he has not spoken to the OpenAI CEO in more than a year.

"Ultimately, I had a big new vision," he said of his resignation.

Sutskever is expected to testify about OpenAI's beginnings and the evolution of its mission.

Former OpenAI CTO Mira Murati is expected to make a roughly hourlong appearance at the trial, but not in person. Instead, jurors will see portions of her videotaped trial deposition.

Murati was an OpenAI superstar since its pre-Microsoft days, and her career spans all the milestones at the center of the trial.

She was one of fewer than 50 employees when she signed on as an OpenAI researcher in 2018, and quickly ascended the corporate ladder. She served as chief technology officer from 2022 to 2024, helming the teams that developed ChatGPT and image generator Dall-E 2.

Murati stepped in for three days as interim CEO after Altman's brief, 2023 firing. Before OpenAI, she was a product manager at Musk's Tesla. She is now CEO of her own $12 billion startup, Thinking Machines Lab.

Jared Birchall, Musk's low-profile financial advisor, has managed the Tesla CEO's billions for more than six years and is scheduled to testify for just over an hour.

Musk's side wants Birchall to detail his boss's millions in contributions to OpenAI, while Altman's team hopes to poke holes in Musk's claim that this "altruism," as he calls it, was betrayed.

Altman's lawyers say they'll ask Birchall about Musk's own for-profit leanings while at OpenAI, including Musk's "directives to create an OpenAI for-profit in 2017."

Altman's side also intends to ask Birchall about "the corporate history" of Musk's competing AI company.