Here's a look at other notable people who resigned or were fired from the Trump administration:
Former Fox News executive Bill Shine has resigned as White House communications director and has joined President Donald Trump's re-election campaign as a senior adviser, the White House confirmed on March 8.
Trump announced on Thursday, Dec. 20, that Defense Secretary Jim Mattis would retire at the end of February. Trump's announcement came a day after he surprised U.S. allies and members of Congress by announcing the withdrawal of U.S. troops from Syria.
In a tweet Dec. 15, President Donald Trump announced that Ryan Zinke was leaving his post as Interior Secretary. Zinke, who served in the Trump administration for two years, had been facing federal investigations into his travel, political activity and potential conflicts of interest.
Trump announced on Dec. 8 that chief of staff John Kelly would leave his job at the end of the year. Kelly, a retired Marine general who served as chief of staff since July 2017, previously served as secretary of homeland security.
Attorney General Jeff Sessions resigned on Nov. 7, 2018. His resignation was effective immediately; ABC News reported that it came at the request of the president.
"We thank Attorney General Jeff Sessions for his service, and wish him well! A permanent replacement will be nominated at a later date," Trump tweeted.
....We thank Attorney General Jeff Sessions for his service, and wish him well! A permanent replacement will be nominated at a later date.— Donald J. Trump (@realDonaldTrump) November 7, 2018
Nikki Haley resigned from her job as ambassador to the United Nations, she announced in a press conference with President Trump. Prior to her appointment in November 2016, Haley was the first female governor of South Carolina.
Haley told reporters that she does not plan to run in 2020.
For months, pressure was mounting against Environmental Protection Agency Administrator Scott Pruitt because of several allegations of ethics violations. On July 5, 2018, Trump tweeted that he had accepted Pruitt's resignation.
The president said Pruitt did an "outstanding job" and "he would always be thankful to him for this." Andrew Wheeler was tapped as Pruitt's replacement.
Omarosa Manigault Newman
The White House said Omarosa Manigault Newman - director of communications for the White House Office of Public Liaison - left the administration in early 2018. The White House aide was initially known as a reality television star, beginning with the first season of "The Apprentice."
White House press secretary Sarah Sanders said in a statement regarding the Homeland Security adviser's resignation: "The President is grateful for Tom's commitment to the safety and security of our great country. Tom led the White House's efforts to protect the homeland from terrorist threats, strengthen our cyber defenses, and respond to an unprecedented series of natural disasters. President Trump thanks him for his patriotic service and wishes him well."
Veterans Affairs Secretary David Shulkin, a lone holdover from the Obama Administration, left his position following an internal investigation alleging ethics violations and misuse of taxpayer dollars. Shulkin claims he resigned from his position, while the White House says he was fired.
National security advisor Gen. H.R. McMaster was replaced by former U.N. Ambassador John Bolton. McMaster was appointed in February 2017 after Trump fired Lt. Gen. Michael Flynn. McMaster faced long-running tension with President Donald Trump in part over his style and disposition in Oval Office briefings, ABC News reported.
On March 16, the president tweeted that Andrew McCabe, deputy director of the FBI, had been fired. He called it a "great day for the hard working men and women of the FBI." McCabe, who was fired just two days before his retirement, kept memos of his conversations with the president much like his former boss James Comey, ABC News reported.
Secretary of State Rex Tillerson left the administration and was replaced by former CIA director Mike Pompeo, the president announced on Twitter on March 13. Trump nominated then-CIA deputy director Gina Haspel to replace Pompeo.
White House chief economic adviser Gary Cohn resigned from his post in early March 2018 following a high-profile battle over tariffs the president wanted to impose on steel and aluminum imports.
Hicks was the longest serving Trump aide before she announced her resignation as White House communications director. Trump praised Hicks for her work over the last three years, saying that he "will miss having her by my side."
The resignation came after Hicks admitted to occasionally telling "white lies" for Trump while being interviewed by the House intelligence panel. She said she had not lied about anything relevant to the Russia investigation.
Former Health and Human Services Secretary Tom Price resigned amidst criticism of his use of private planes for government travel. Price's departure came as he was being investigated by the inspector general's office at the U.S. Department of Health and Human Services.
Bannon served as the White House's chief strategist before resigning from his post on August 14, exactly one year after he joined Trump's campaign. He returned to leading the conservative media outlet Breitbart News following his resignation.
Scaramucci served as White House communications director for just 11 days before he resigned. During his time as communications director, Scaramucci had an expletive-riddden phone call with New Yorker reporter Ryan Lizza in which he criticized Reince Priebus and Steve Bannon.
The White House press secretary resigned after a tumultuous six-month run on the podium where he often had run-ins with the press. His daily televised briefings made him the subject of a high-profile Saturday Night Live parody by Melissa McCarthy.
Trump's first National Security Advisor, former Lieutenant General Michael Flynn, had the shortest tenure in that position. After just 24 days, Flynn resigned on February 13, after The Washington Post stated he had spoken with Russian Ambassador Sergey Kislyak during the transition of power.
Trump fired the FBI director on May 9, 3-and-a-half years into a 10-year term. He initially claimed that Comey's firing was due to his handling of the Hillary Clinton investigation during the 2016 election, but he also admitted to NBC's Lester Holt that it was because he was unhappy with the investigation into his own campaign's ties with Russia.
Former RNC chair Reince Priebus was appointed to the powerful position of Chief of Staff but unceremoniously fired, seemingly via tweet, on July 28. Trump announced that General John Kelly, serving as Secretary of Homeland Security, would be replacing him.
I am pleased to inform you that I have just named General/Secretary John F Kelly as White House Chief of Staff. He is a Great American....— Donald J. Trump (@realDonaldTrump) July 28, 2017
Acting Attorney General Sally Yates was fired just hours after she announced the Justice Department would not defend Trump's controversial executive order temporarily banning all refugees and travelers from certain countries.
The Associated Press contributed to this report.