John Adams and Thomas Jefferson
The stuffy Massachusetts lawyer John Adams and the regal Renaissance man Thomas Jefferson were both Founding Fathers and BFFs. Together, they helped ignite the American Revolution, give birth to a new country, and even starred together in an excellent mini-series on HBO. But during Jefferson's tenure as Adams vice president, their relationship soured. Jefferson would eventually run against Adams to become the third President of the United States. The ideological split between Adams and Jefferson survives to this day whenever the topic of states-rights and a strong Federal government come up. While the two spent time as bitter political rivals, they eventually buried old grudges late in life and even died on the same day — July 4th, 1826.