Lewandowski, a retired New Hampshire state police officer and political activist who had never run a presidential campaign before, helped shepherd Trump to the Republican nomination, an amazing feat by any measure. But along the way, he left behind a trail of bizarre moments that have come to symbolize this unorthodox campaign season.
Throughout the campaign, Trump's greatest liability was also his strongest asset: He was brash, outspoken, crude, undisciplined as a speaker and unwieldy in his policy positions.
That was just fine with Lewandowski.
Several media profiles of the campaign's operations included the detail that Corey regularly reminded staffers that they shouldn't try to rein in the boss, telling them to "Let Trump be Trump."
"Those words have been scrawled on his office white board since Mr. Trump announced his run June 16," the Wall Street Journal
wrote in February.
But as the campaign began to round the bend into the general election, Trump's unpredictable behavior began to lose its appeal, requiring a more disciplined operation. Lewandowski's departure could put the operation in the hands of more experienced campaigners.
2) He grabbed a reporter and then said he hadn't
Lewandowski burst out of the shadows in March when a Breitbart News reporter accused him of grabbing her by the arm while she attempted to ask Trump a question after an event in Florida.
The reporter, Michelle Fields — who left Breitbart after the incident and now works for the Huffington Post — said Lewandowski yanked her arm, nearly pulling her to the ground. She later posted a photo of bruises she alleged were from the encounter.
Lewandowski denied any involvement, but he was later contradicted by video evidence.
A few weeks later, police in Jupiter, Florida, released CCTV footage of the incident, which clearly showed Lewandowski grabbing Fields. But in April, the Palm Beach County Florida State Attorney announced the state would not charge him with a crime.
3) Trump stood by him
The incident with Fields created a media firestorm, with calls on Trump to fire Lewandowski. Instead, the mogul invited him on stage during a victory speech after winning contests in Florida, Illinois and North Carolina.
"Corey, good job Corey," Trump said, adding that journalists are "disgusting people."
Trump's move was a clear sign that he was standing by Lewandowski amid the uproar, and it created the impression that Trump was fiercely loyal to his staff.
"I can't destroy a man. I can't destroy him," Trump said later when asked why Lewandowski wasn't fired. "He's got a beautiful wife and children, and I'm not gonna destroy a man for that."
That loyalty did not extend into the general election season, when Lewandowski was ultimately fired in June after several weeks of campaign infighting and missteps.
4) Lewandowski's media tactics
When BuzzFeed News called the Trump campaign for comment about an Arizona man with ties to the campaign who was fired for writing "Islamophobic" and "racially charged" Facebook posts, Lewandowski was caught on a recorded line
organizing a plan to mislead the news organization.
Trump's campaign had spoken to Arizona Republican operative Aaron Borders, who had organized events for Trump in the past, about joining the campaign in a formal role. But when the social media posts were made public, the campaign wrote him off as just an "over-zealous volunteer."
But then Borders supplied a recording of Lewandowski hatching a plan to cover up the campaign's involvement with him.
"We don't have staff stories and we don't have staff in stories about things ... We'll just tell BuzzFeed that there's no formal relationship, that you're an overzealous volunteer, and that you're not part of the campaign in any way shape or form, regardless of what the story says," the recording, provided to Buzzfeed, showed Lewandowski saying.
When Buzzfeed posted the story, Lewandowski threatened a lawsuit against Borders, saying, "I'm going to sue your f---- ass to next year, you know that, right?"
When Buzzfeed asked about that, Lewandowski denied ever saying it, despite there being a recording of him saying it.
The interaction between Lewandowski, campaign supporters and the media, is a testament to how he ran the shop.
At campaign rallies, Lewandowski acted as an enforcer, threatening to revoke credentials from reporters who didn't follow his directions. (The Trump campaign corralled journalists into a "pen" at events.)
5) Internal frustration with Lewandowski goes public
Lewandowski was known for being short-tempered and direct with staff, a leadership trait that reportedly frustrated many who worked under him.
The campaign did a pretty good job keeping that under wraps, but in May, The New York Post
reported that Trump campaign spokeswoman was spotted berating Lewandowski on a New York street corner.
"Hope was screaming at Corey, 'I am done with you!'" The Post reported an anonymous source saying. "It was ugly, she was doubled over with her fists clenched. He stood there looking shocked with his hands on his head."
According to the article, the disagreement was over a power struggle between Lewandowski and Paul Manafort, who joined the campaign this spring.
Ultimately, as we learned this week, Manafort won.