Lyndon B. Johnson: Slytherin
Johnson had an exceedingly strong work ethic, which would have made him a worthy Hufflepuffer. He could, at times, show courage, though his natural tendency seems to have been to avoid personal danger. Nevertheless, Johnson’s ambition and his ruthless pursuit of power make him a natural fit for Slytherin.
John F. Kennedy: Slytherin
Perhaps because Harry Potter starts the series as an eleven-year old, the series does not get into too much sexual content. Sure there are teenage crushes, and the epilogue shows us the offspring of Harry & Ginny, Ron & Hermione. But there’s no lothario House and/or character that might be a good parallel to JFK. So we’re going with Slytherin since dead people in Chicago certainly weren’t going to vote by themselves without JFK’s ambition.
Nixon: Hufflepuff
The first instinct is to put Nixon in Slytherin, but that would be unfair to both Nixon and Slytherin. Nixon was ambitious, but he was a dogged worker. In high school, he managed to make the football team, though he was a poor athlete and only played third string. In college, he once searched for an outhouse to top a bonfire until he found a rare four-holer. Nixon craved approval and love, which seems to us a Hufflepuff trait.