MOSCOW (AP) — An investigation by special counsel Robert Mueller into an elaborate Russian operation that sought to meddle in the 2016 U.S. presidential election and try to help Donald Trump win the White House has cast a spotlight on more than a dozen Russian nationals, including billionaires, an elusive linguist, an ambassador and a pop star. A look at some of the cast of characters:

Putin’s chef

Yevgeny Prigozhin, 57, earned the nickname of "Putin's chef" for hosting Russian President Vladimir Putin and his foreign dignitaries at his restaurant and catering important Kremlin events. A former convict, he now runs companies worth hundreds of millions of dollars, thanks to his willingness to do favors for Putin that others would find too risky.

Prigozhin was indicted in the U.S. last year in an elaborate plot to disrupt the 2016 election. The indictment said he funded the Internet Research Agency, a "troll factory" in Russia's St. Petersburg that used social media accounts to "sow discord in the U.S. political system."

But he also is the suspected mastermind of a company called Wagner that has been sending private military contractors to fight in Syria, Ukraine and African countries.

Putin has dismissed charges against the St. Petersburg native and his employees as "ridiculous," mocking the West for falling "so low" to be suspecting "a restaurateur from Russia" of influencing the U.S. election.

The elusive linguist

Konstantin Kilimnik worked for Paul Manafort starting in the early 2000s. He is described as a fixer, translator or office manager and helped the political consultant formulate his pitches to clients in Russia and Ukraine.

The FBI says Kilimnik has ties to Russian military intelligence, but he has denied that.

U.S. officials regarded Kilimnik as Manafort's key aide during their work on behalf of pro-Russian Viktor Yanukovych, who became the president of Ukraine in 2010.

Born in what was then Soviet Ukraine, Kilimnik got a degree in linguistics from a military university and in 1995 began working as a translator for the International Republican Institute in Moscow, a U.S.-government-funded nonprofit that promotes democracy.

Court documents filed by attorneys with Mueller's office showed Manafort shared polling data from the Trump campaign with Kilimnik. The two also discussed a Russia-Ukraine peace plan several times including during an August 2016 meeting at a cigar bar in New York. A Mueller prosecutor has said that meeting goes to the "heart" of the Russia investigation, but additional details have been blacked out in court documents.

Even after Manafort lost his campaign job and was indicted by Mueller on charges related to his foreign lobbying work, U.S. prosecutors alleged, Kilimnik helped ghost-write an op-ed defending Manafort.

Kilimnik was indicted alongside Manafort on witness tampering charges. He reportedly lives in Russia, where he keeps a low profile and refuses to talk to reporters.

The ambassador

Career diplomat Sergey Kislyak was Russia's ambassador in Washington from 2008 until 2017, when he was called home amid scrutiny of his recurrent meetings with the Trump campaign staff as the Mueller probe gained speed.

The low-key official with 40 years of diplomatic service was thrust into the limelight in December 2016 when Michael Flynn, who would become Trump's national security adviser, held conversations with Kislyak and asked him not to escalate a diplomatic fight with the U.S. over punishment levied by the Obama administration on Moscow.

Kislyak also had conversations with Trump's son-in-law Jared Kushner at Trump Tower that year and also met with then-Sen. Jeff Sessions, later Trump's attorney general.

Flynn later pleaded guilty to lying to the FBI about his conversations with Kislyak.

The 68-year-old Kislyak, who is not accused of any wrongdoing, has vehemently denied that he or any embassy staff tried to disrupt the 2016 election. He currently sits in the upper chamber of the Russian parliament.

The property developer and the pop star

Property developer Aras Agalarov, 63, and his 39-year-old pop singer son, Emin, have had a relationship with Trump dating to their bid to host the 2013 Miss Universe pageant in Moscow.

The elder Agalarov told AP in 2017 that he first met Trump in the U.S. when he and Emin flew in to negotiate the rights to hold the pageant. They hit it off and have had a friendly relationship ever since. Agalarov told the Russian edition of Forbes that his company spent about $20 million on the pageant. Agalarov also said that he offered the future U.S. president a site for a Trump tower in Moscow, but "it didn't come to signing any deals."

The Agalarovs maintained ties with Trump, and it was Emin who, through his British publicist, helped arrange a June 9, 2016, meeting at Trump Tower in New York with a Russian government-connected lawyer who was purported to have documents that could "incriminate" candidate Hillary Clinton in support of the Trump campaign. The meeting was attended by Donald Trump Jr., along with Manafort and Kushner. The American participants would later say the meeting was a bust in terms of gathering derogatory information on Clinton, consumed by a lengthy discussion of Russian adoption and U.S. sanctions.

The younger Agalarov last month canceled his upcoming shows in the U.S., citing "circumstances beyond my control." His father continues to operate a successful real estate and construction business. Neither father nor son is accused of any wrongdoing.

The lawyer

Moscow lawyer Natalia Veselnitskaya was thrust into the Russia probe when it emerged that she attended the Trump Tower meeting in June 2016. Leaked documents suggested that the 43-year-old Veselnitskaya went to the meeting as part of efforts to help her clients try to overturn U.S. sanctions — one of the Kremlin's strategic goals.

While Veselnitskaya has denied acting on behalf of Russian officials, scores of emails and documents shared with the AP show she served as a ghostwriter for top Russian government lawyers and received assistance from senior Interior Ministry personnel.

In January, Veselnitskaya was indicted by federal prosecutors in New York on one count of obstruction of justice in an unrelated tax fraud case that alleged she teamed up with a senior Russian prosecutor and submitted deceptive declarations in a civil proceeding.

The aluminum mogul

Oleg Deripaska made his billions in the aluminum industry in the rags-to-riches privatization era that followed the collapse of the Soviet Union and was involved in infrastructure development for the 2014 Sochi Olympics, one of Putin's pet projects. Deripaska once hired Manafort as a consultant, and prosecutors disclosed he provided a Manafort company with a $10 million loan around 2010. Manafort offered to provide Deripaska with private briefings during the 2016 election campaign, but there is no evidence such briefings ever occurred.

The 51-year-old was trained as a physicist in the late years of the Soviet Union and became a major player on the Russian metals market even before his 30th birthday. Even among Russian billionaires, Deripaska is notable for his closeness to Putin.

Deripaska and his companies were hit with crippling U.S. sanctions last year over Russia's "malign activity" including Moscow's seizure of Crimea from Ukraine. But the U.S. Treasury last month lifted sanctions on three Russian companies owned by Deripaska, reversing a move that wreaked havoc on global aluminum markets, after the oligarch restructured the companies and reduced his share in them.

The oligarch at the inauguration

Billionaire Viktor Vekselberg has long ties to the U.S. including a green card he once held and homes in New York and Connecticut. The 61-year-old Ukrainian-born businessman, estimated to be worth $13 billion, heads the Moscow-based Renova Group, a conglomerate encompassing metals, mining, tech and other assets.

Vekselberg built his fortune by investing in the aluminum and oil industries in the post-Soviet era. As of mid-February, a company controlled by Vekselberg and a group of partners owned 22.5 percent in Deripaska's Rusal, a metals company that was hit with the U.S. sanctions, according to a letter sent by Senate Intelligence Committee ranking Democrat Mark Warner to Treasury Secretary Steven Mnuchin. Deripaska subsequently agreed to cede control of Rusal in exchange for the sanctions relief.

As a rich and powerful Russian, Vekselberg is presumed to operate with Putin's tacit approval. He has used his wealth to exert influence in the U.S., including the Skolkovo Foundation, a Russian government-backed nonprofit aimed at winning U.S. and Western tech investment in Russia.

Vekselberg has worked closely with his American cousin, Andrew Intrater, who heads the New York investment management firm Columbus Nova. Media attention zeroed in on Vekselberg and Intrater when the attorney for the adult film actress known as Stormy Daniels released a memo claiming the cousins routed about $500,000 through Columbus Nova to a shell company set up by Trump's attorney Michael Cohen. Columbus Nova denied that Vekselberg played any role in its payments to Cohen.

Several days before Trump's inauguration, Vekselberg and Intrater met with Cohen at Trump Tower, one of several meetings between Trump intimates and high-level Russians during the 2016 campaign and transition.

Vekselberg also was targeted with U.S. Treasury Department sanctions, which cited his ties to Putin, after he was questioned by Mueller’s staff on a visit to the U.S. All of Vekselberg’s assets in the U.S. are frozen and U.S. companies are forbidden from doing business with him and his entities.