WASHINGTON — President Trump’s Ukraine scandal reaches the highest levels of his administration, roping his Attorney General William Barr and Secretary of State Mike Pompeo into a widening controversy that’s unleashed an impeachment inquiry.

Democrats have subpoenaed Pompeo for documents and demanded Barr appear before the Senate to speak about allegations that Trump pressed Ukraine to interfere in the 2020 election.

But the affair has also tossed plenty of lesser-known characters into the national limelight. These once-fringe players now look set for feature roles in the historic impeachment battle.

They run the spectrum from experienced American diplomats to a Soviet-born businessman who trades in coffee and baby food. But many share a common thread: a connection to Trump’s personal attorney turned Ukraine conspiracy hunter, Rudy Giuliani.

As Democrats’ impeachment inquiry gears up, here are some of the names you’re about to hear a lot more of in the weeks ahead.

The Lawyer: Rudy Giuliani

Rudy Giuliani hardly kept his efforts to push Ukraine to investigate Joe Biden a secret: He’s been tweeting about it for months.

Now he’s in Congressional crosshairs. House Democrats subpoenaed the former New York mayor this week for all his communications about Ukraine, Biden and more, in an attempt to figure out exactly what he’s been up to.

Giuliani is a controversial figure even in GOP circles. Some top Republicans worry he’s doing more harm than good with his constant television appearances, including Republican Sen. Lindsey Graham, who recently told reporters, “I’m not sure he’s helping the president by being on TV every 15 minutes.”

A still-unidentified intelligence community whistleblower tagged Giuliani as a “central player” in Trump’s apparent effort to pressure Ukrainian President Volodymyr Zelensky to dig up dirt on Biden and his son Hunter, in a complaint filed in August.

Since then, Giuliani has attempted to argue that the State Department knew what he was doing, while making surreally disjointed appearances on cable news.

The Diplomat: Kurt Volker

Trump’s Special Envoy to Ukraine Kurt Volker was the first person to resign in the scandal — in what may be a worrying sign for Trump.

Volker helped introduce Giuliani to a key advisor to Ukraine’s president, Andrey Yermak, this summer. When Giuliani canceled a planned trip to Ukraine in the spring, grumbling about “enemies of the president” in Ukraine, Yermak asked Volker to connect him with Giuliani.

Volker then had breakfast with Giuliani to chat about it — and later put Giuliani and Yermak in touch.

“Mr. Mayor — really enjoyed breakfast this morning,” Volker wrote Giuliani in a text message that Giuliani’s been waving around on cable television to prove the State Department knew about his outreach to Ukraine.

House Democrats want to interview the grey-haired diplomat this Thursday. Now that he’s left the Trump administration, he might feel free to tell Democrats everything he knows, instead of clamming up like others in Trump’s circle have.

But they’ll face resistance from Pompeo, who blasted Democrats’ attempts to call current and former U.S. diplomats to Capitol Hill as “not feasible.” But Volker, once a widely respected ambassador to NATO, was never seen as a hardcore Trumper, and it remains uncertain how he’ll play the situation.

Democrats will want to ask Volker all about his interactions with Giuliani and Yermak, and exactly what he and the former mayor chatted about over breakfast in July.

The Adviser: Andrey Yermak

Yermak has said he reached out to Giuliani after hearing that Trump’s lawyer had canceled his trip to Ukraine while complaining about Trump’s “enemies” there.

Yermak has claimed he wanted to “clear up the situation.” After reaching out to Volker and chatting with Giuliani on the phone, Yermak met Giuliani in Madrid, about a week after Trump’s notorious July 25 phone call with Zelensky.

“I talked to him about the whole package,” Giuliani later told The Washington Post about that meeting.

Yermak said they discussed efforts to fight corruption in Ukraine — a term that Trump’s circle often uses when they talk about investigating Biden.

But it’s not clear Yermak actually did anything to help launch any investigations in Ukraine, and he now says he wants his country to stay out of American domestic politics.

“What is happening there — it’s their own domestic political games,” Yermak said of Trump’s latest scandal on Ukraine’s 1+1 channel on Sunday. “We will not take part in this in any way.”

The Prosecutor: Viktor Shokhin

Giuliani’s adventures in Ukraine have focused on the dubious career history of the country’s controversial former top cop: Viktor Shokhin.

Trump and Giuliani argue, in claims that do not appear supported by the evidence, that Shokhin was hounded out of office by then–Vice President Joe Biden in early 2016. Biden, they claim, pushed Ukraine to fire Shokhin to block any investigation of a Ukrainian gas company called Burisma, on which Hunter Biden had a paid board seat.

But there’s a big flaw in that narrative: Shokhin was widely seen as stopping corruption investigations, not launching them.

Shokhin was a lightning rod for controversy during his tenure as Ukraine’s general prosecutor. He was accused of slow-walking probes into members of former Ukrainian President Viktor Yanukovych’s notoriously corrupt administration, and his departure was hailed by the U.S. State Department in early 2016 as “a signal of Ukraine’s seriousness about its reform process.”

Shokhin was “widely criticized for turning a blind eye to corrupt practices and for defending the interests of a venal and entrenched elite,” The New York Times reported at the time of his ouster.

Shokhin showed “clear allegiance” to “the corrupt status quo” during his tenure, according to a report by The Kennan Institute. The European Union and IMF also wanted him gone, notably.

Meanwhile, Shokhlin’s successor, Yuri Lutsenko, has said he’s unaware of any wrongdoing by Joe or Hunter Biden.

The South Florida Crew: Lev Parnas and Igor Fruman

Giuliani got help navigating Ukraine from two Soviet-born businessmen living in South Florida, who have been called up for questioning by House Democrats about their role in connecting Giuliani with Ukrainian officials.

One of them, Lev Parnas, a former stock broker, boasted that he personally arranged a Skype call between Giuliani and Shokhin in 2018.

“I arranged the Shokin call with the mayor," Parnas recently told NPR.

Giuliani has identified Parnas and his business partner, the import-export merchant and real estate investor Igor Fruman, as his “clients.” But the two men appear to have also been his guides to Ukraine, introducing Giuliani to three current and former senior Ukrainian prosecutors to discuss politically sensitive information, according to a detailed profile of the two men by the Organized Crime and Corruption Reporting Project and BuzzFeed News.

Parnas told The Miami Herald last week that he gave information on alleged wrongdoing by the Bidens to Giuliani.

“I got certain information, and I thought it was my duty to hand it over,” Parnas told the paper.

House Democrats have called in both men for depositions next week to find out more about their ties to Giuliani and the Trump administration — which go deeper than just the recent Ukraine scandal.

Parnas and Fruman made hundreds of thousands of dollars in political donations to Republicans, while facing lawsuits from disgruntled investors over unpaid debts, according to ABC News. That includes a $325,000 donation to a Trump-allied political action committee in 2018 that's now facing scrutiny from federal regulators.

A Reuters reporter spotted Giuliani and Parnas having coffee together at the Trump International Hotel in Washington last week, just a few blocks from the White House.