Michael Flynn: Former US national security adviser
Michael Flynn's short tenure as Donald Trump's national security adviser ended in controversy when he resigned over contacts he had made with Russia before Mr Trump took office.
After just 23 days on the job, Mr Flynn was forced out over revelations that he had discussed lifting US sanctions on Russia with their ambassador to Washington, and that he lied to the US vice-president about that conversation.
Since his departure, revelations have kept on coming.
Since Mr Flynn left the White House the Pentagon has launched an investigation into whether he failed to disclose payments from Russian and Turkish lobbyists that he was given for speeches and consulting work.
In March, he registered with the US government as a "foreign agent" due to his work for the Turkish government.
Former President Barack Obama warned Mr Trump against hiring the former general less than 48 hours after the November election during a conversation inside the Oval Office.
Mr Flynn has requested immunity from the congressional committees investigating alleged Russian meddling on the 2016 election in exchange for his testimony, but so far no committee has taken him up on the offer.
"As a former military officer, you simply cannot take money from Russia, Turkey or anybody else," said Republican Congressman Jason Chaffetz.
"And it appears as if he did take that money. It was inappropriate, and there are repercussions for a violation of law."
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Mr Flynn was all but written off two years ago when he was removed from his post as a Pentagon intelligence chief by Mr Obama.
But the retired US Army three-star lieutenant-general was one of Donald Trump's closest advisers and most ardent supporters during the 2016 campaign.
His importance was underlined just days before his resignation, when he was with the president at his Mar-a-Lago estate in Florida as he hosted his first foreign leader there, Japanese Prime Minister Shinzo Abe.
In the past, Mr Flynn has complained he was fired from the Defence Intelligence Agency (DIA) in 2014 after just two years for telling hard truths about the war on Islamist extremism.
Mr Flynn said the US is losing a global war against Islamist extremism that could last for generations.
But insiders have suggested his exit at the DIA may have been related to his unpopular overhaul of the agency.
Former US officials who worked closely with him described him as extremely smart, though a poor manager.
Indeed, Mr Flynn, a father-of-two who married his high-school sweetheart, went on to become one of the Obama administration's most outspoken critics, all the more surprising as he was a life-long Democrat.
But the Rhode Islander said he no longer recognised the Democrats as the party he once supported.
He instead decided to align himself with Mr Trump, a man whom he rated as a hustler and outsider like himself, part of a larger fight against "the dishonesty and deceit of our government".
Mr Flynn was an almost evangelical supporter of Mr Trump.
"We just went through a revolution," he said after the businessman's shock election victory.
"This is probably the biggest election in our nation's history, since bringing on George Washington when he decided not to be a king. That's how important this is."
Mr Flynn and Mr Trump shared many views, including the advantages of closer ties with Russia, renegotiating the Iran deal and combating the threat from Islamic State militants.
Like Mr Trump, Mr Flynn called the 2003 invasion of Iraq a strategic blunder.
Even the areas where the two disagreed at first were quickly smoothed over.
Gen Flynn's declaration that he was pro-choice was quickly amended to pro-life in July, after it sparked outrage among Trump supporters.
And, like Mr Trump, he was no stranger to controversy.
Back during his days at the DIA, he apologised for a presentation which suggested make-up made women "more attractive" and encouraged people to dress for their body shape.
He later said neither he nor the agency "condone this briefing".
In 2016, his appearance at a banquet held in honour of the Russian government, where Gen Flynn sat two seats away from Vladimir Putin, raised eyebrows, with his apparent warmth towards Moscow concerning some national security experts.
More controversial yet have been his views on Islam.
In February 2016, he tweeted "fear of Muslims is RATIONAL".
In August, he spoke at an event in Dallas, Texas, for an anti-Islamist group Act for America, saying that Islam "is a political ideology" and that it "definitely hides behind being a religion".
Some expressed concern at how much influence Mr Flynn could wield over a president with little international experience.
But for all his critics, there were those who stood behind Mr Flynn, a man who built a reputation as an astute intelligence professional during his three decades in the US Army.
David Deptula, a retired air force lieutenant general who used to work with him, praised his willingness to "speak truth to power and not politicise his answers".