Facebook has been slammed for failing to protect the data of more than 50 million users. Their data was used to further conservative political projects, including Brexit and Donald Trump's presidential victory. From a former White House strategist to a Canadian whistle blower, here are the people involved in what some are describing as Facebook's largest data breach.

A 28-year-old Canadian data analytics expert first blew the whistle on the scandal to Britain’s Observer newspaper. Christopher Wylie claims he set up the project for Cambridge Analytica and helped forge ties with Donald Trump’s campaign. He revealed that millions of profiles were hijacked to influence the election. Cambridge Analytica says Wylie has been "misrepresenting himself and the company."

Cambridge Analytica CEO, Alexander Nix, was one of several senior executives filmed by an undercover reporter from Britain's Channel 4. Nix claimed credit for Donald Trump's 2016 electoral victory. He also said his political consultancy could feed untraceable messages on social media. Executives bragged that the firm could use misinformation, bribery and even prostitutes to help win elections.

A Moldovan-born Cambridge University researcher developed a personality app that harvested the personal data of 30 million Facebook users. Aleksandr Kogan said he passed the information to Cambridge Analytica, under assurances that what he was doing was legal. But now he says the research firm and Facebook are scapegoating him over the scandal.

Facebook CEO Mark Zuckerberg was criticized for waiting for four days to respond to the scandal. His social media network claims to be the victim of the whole saga, insisting it was unaware of how the data was being used. Still, Zuckerberg has been summoned by the British and European parliaments, while US consumer regulators have launched an investigation into the firm's use of personal data.

Trump's former strategist Steve Bannon helped develop the populist, anti-Washington message that helped the billionaire win the White House. A founding member of right-wing outlet Breitbart News, Bannon is a former board member of Cambridge Analytica and brought in wealthy businessman Robert Mercer as a financial backer. He left the White House last August and Trump has since cut him off.

Playboy Enterprises said it is closing its Facebook pages as the scandal surrounding the social network grows. Playboy said the privacy scandal was the final straw after long having had difficulty posting to the site due to Facebook's strict rules to keep nudity off the platform. Some 25 million people interacted with Playboy's Facebook pages.

Elon Musk, the billionaire entrepreneur behind electric car manufacturer Tesla and rocket producer SpaceX, wrote on Twitter he would delete both companies' Facebook accounts. The decision appeared to be spontaneous after Musk wrote he "didn't realize" a Facebook account for SpaceX even existed. The accounts of both companies each had around 2.6 million followers before they were deleted.

The company behind popular web browser Firefox said in a statement that it was "pressing pause" on its Facebook advertising. But it said it would not delete its Facebook account. Instead, the company would stop posting regular updates on the account. "When Facebook takes stronger action in how it shares customer data ... we'll consider returning," it said.

Commerzbank, one of Germany's largest banks, said it was pausing its Facebook advertising. The head of the company's brand management told German business newspaper "Handelsblatt:" "We're taking a break with our advertising on Facebook. Data protection and maintaining a good brand are important to us." He added that the company would wait and see before it made any further decisions.

The co-founder of messaging service WhatsApp, Brian Acton, wrote in a March 20 post on Twitter: "It is time. #deletefacebook." Acton became a billionaire after selling WhatsApp to Facebook in 2014. He recently invested in a rival messaging app, Signal, after leaving WhatsApp in 2017. Acton had a history with Facebook before 2014. He unsuccessfully interviewed for a job at the company in 2009.

The US-based speaker manufacturer said it was pulling its advertising from Facebook and other social media platforms, including Facebook-owned Instagram. Sonos said recent revelations "raised questions" about whether Facebook had done enough to safeguard user privacy. But it said it would not completely "abandon" Facebook because it was an "incredibly effective" service.

The German food corporation let its Twitter followers vote on whether it should delete its Facebook account. "We'll delete our Facebook page for 1,000 retweets," it wrote in a March 21 post. It was quickly retweeted over 1,000 times, leading the company to deactivate its Facebook page. But it reactivated the account a day later, writing on Twitter that it "couldn't be" without Facebook.

Asked about the decision of some companies to leave the social network, Facebook said: "Most of the businesses we've spoken with this week are pleased with the steps we've outlined to better protect people's data, and they have confidence that we'll respond to these challenges and become a better partner and company as a result."