When presidents or prime ministers are elected, there's an expectation the individuals will spend a certain number of days, weeks, and months in service to the government and the people. It extends even further when monarchs accede to the throne, often thought to their role for years or decades.
While leadership positions can come with terms of office attached to them or be (theoretically) for life, that's not always how events have played out. Coups, untimely deaths, scandal - these can all result in a quick and sudden end to one's term. From the violent ousting of a president or a smooth transition between prime ministers, a short time in office may result in an individual being completely overlooked.
Don't blink or you may miss them - vote up the shortest times in office from history.