There is only one absolute monarch left in Europe. He (women are ineligible for this job) rules over an extremely small piece of territory. But his influence is far greater than the population and land area of his state would indicate. And, in a situation that (I believe) is unique among independent states, he is elected by a group of voters, most of whom are from other countries.
That man is Pope Benedict XVI, who, in addition to being the leader of the Roman Catholic Church, is head of state of Vatican City State. Its area is 0.44 square miles, and its population is 826.
According to this article is Slate's "Explainer" column, there is no mechanism for removing a pope from office. Accusations that, several years ago, as an archbishop, Benedict (then known as Joseph Ratzinger) participated in a cover-up of clergy sexual abuse scandals, bring those scandals closer to a pope than ever before. The question is whether he could be forced out of office. Christopher Beam's research indicates that the answer is "no". However, there is precedent (though not in recent centuries) for a pope to resign.
The issue of papal resignation was raised toward the end of the long reign of Pope John Paul II. During the last few years before his 2005 death, John Paul's physical decline led to suggestions that he should retire. As it happened, he died in office, apparently able to perform his duties until he was very near the end.
We'll need to wait and see whether pressure will be brought on Benedict to resign.
Normally, the fate of the head of state of such a small place would not generate this much attention. But, of course, Benedict's dual religious and political role magnifies his importance in world affairs. Joseph Stalin, when confronted with the reality of papal influence, is said to have asked "how many divisions does the pope have?" Stalin's successors leading the Soviet Union found out to their chagrin that, figuratively speaking, a pope can lead a huge army, when John Paul II played a major role in dismantling the European Marxist-Leninist regimes.