Some quit before he was in post, others after he was confirmed.
Resigned before Boris Johnson became PM
Philip Hammond, the UK's Chancellor of the Exchequer or the head of the finance ministry, resigned shortly after Theresa May's final Prime Minister's Questions on Wednesday.
In his resignation letter, which was posted to Twitter, he said it had been "a privilege" to serve in May's cabinet for the past three years, but that he believed her successor "must be free to choose a Chancellor who is fully aligned with his policy position".
He added: "Most importantly, we bequeath to our successors genuine choices, once a Brexit deal is done: the ability to choose, within the fiscal rules, between increasing public spending, reduced taxes, higher investment or progress towards faster debt reduction - or some combination of all four.
"After a decade when the aftermath of the 2008-09 recession meant we had no choices, this is a luxury which our successors should use wisely."
Hammond was expected to be sacked if he did not follow through on his threat to resign when Johnson took office.
Johnson is believed to require a "loyalty pledge" for all his future cabinet members to accept a possible no-deal Brexit on October 31.
"I am sure I am not going to be sacked because I am going to resign before we get to that point," Hammond said over the weekend.
"Assuming that Boris Johnson becomes prime minister, I understand that his conditions for serving in his government would include accepting a no-deal (EU) exit on the 31st of October. That is not something I could ever sign up to."
Hammond has vocally opposed a no-deal Brexit scenario in separate occasions. He warned last week that the UK would "lose control" of many key sectors of its economy, including the crucial trade link at the French port of Calais, if the country leaves the EU without a deal.
May's de facto deputy, David Lidington, did not give a specific reason for his resignation instead saying "it was the right moment to move on".
He did add, however, that he wanted the UK to leave the EU with a deal, potentially putting him at odds with Johnson.
Sir Alan Duncan
In his resignation letter, Sir Alan Duncan, a minister in the Foreign Office, paid tribute to outgoing Prime Minister Theresa May.
He said she had an "unstinting sense of duty" and "faultless dignity".
"I am only sorry that your three years as Prime Minister have been brought to an end," wrote Sir Alan. "You deserved better, but please take lasting comfort from the knowledge that your self-esteem can, and will forever, far exceed that of your critics."
Duncan has criticised the conduct of Johnson, the favourite to become Britain's next prime minister, in recent weeks, particularly in the case involving leaked quotes from former ambassador to the US Kim Darroch.
He said: "Boris Johnson has basically thrown our top ambassador under the bus. His disregard for Sir Kim Darroch and his refusal to back him was pretty contemptible and not in the interests of the country he is hoping to lead."
Stewart's resignation on Wednesday came as no surprise as the MP for Penrith and The Border had already publicly acknowledged that he would not serve in a cabinet led by Johnson.
Unlike his fellow MPs, Stewart's resignation confirmation was a little different, having taken a screenshot of the ticker tape announcement on a Sky News broadcast.
Stewart, who got down to the final five in the race to replace May as Conservative Party leader, accompanied the picture with a simple upside-down emoji.
Justice minister David Gauke said he was resigning because he believed that the best way to quit the EU was with a deal.
"Given Boris' stated policy of leaving the EU by 31 October at all costs, I am not willing to serve in his government," he wrote in his resignation letter.
"I have grave concerns about leaving the EU without a deal and so I feel it is time for me to return to the backbenches," wrote Anne Milton, a skills and apprenticeships minister, wrote in her resignation letter.
Johnson has said he is prepared for the UK to quit the EU on October 31 without a deal in place if agreement cannot be reached with Brussels.
Resigned after Boris Johnson became PM
"Sadly, I will be leaving the Government. It has been a privilege to have served as Secretary of State for International Trade these past 3 years," wrote Dr Liam Fox on Twitter, shortly after Boris Johnson made his first speech as prime minister.
There was nothing else in Fox's departing tweets to suggest that he was at odds with Johnson over policy.
Business minister Greg Clark announced he was leaving the government without suggesting a disagreement of policy with the new PM.