A look at four past presidents who stepped forward to accept responsibility for events that happened on their watch. (The Washington Post)

President Obama apologized Thursday to the Americans who lost their health plans as a result of the federal health-care law, following immense criticism of his longstanding refrain that Americans could keep their plans if they wanted.

It's not every day that presidents apologize -- which is why it was such a big deal. It's even rarer that presidents apologize in the middle of a firestorm for decisions their administrations made. That's what Obama just did.

It all got us to thinking about the other big presidential apologies and kind-of-sort-of-apologies throughout history. Some of the most notable ones came from presidents still in office, while others arrived after they left. The circumstances and precise wording of the apologies has varied, it should be noted.

Below is a list of the seven most memorable ones, in chronological order. What did we miss? Let us know in the comments section.

1. John F. Kennedy apologizes for the Bay of Pigs invasion (1961). In a speech after the disastrous invasion of Cuba, Kennedy said we intend "to profit from this lesson."

2. Richard Nixon apologizes for Watergate (1977). Five years after the Watergate scandal that forced him from office, Nixon sat down for now-famous interviews with British journalist David Frost in which he said he "let the American people down."

3. Ronald Reagan expresses regret for Iran-Contra (1987). "This happened on my watch," Reagan told the nation about the complicated scandal involving arms sales to Iran.

4. Bill Clinton's Rwanda apology (1998). Clinton said in a speech that the international community "did not react quickly enough after the killing began" during the Rwandan genocide of 1994.

5. Clinton says he "misled people" about Monica Lewinsky (1998). Clinton addressed the nation about his affair with Monica Lewinsky, saying, "I misled people, including even my wife. I deeply regret that."

6. Obama apologizes for "Special Olympics" remark (2009). The president apologized to the chairman of the Special Olympics board after invoking the event to describe his poor bowling skills.

7. Obama's health-care "sorry." The president apologized Thursday to Americans losing their health plans in an interview with NBC News.