Jan Jessenius (27. 12. 1566 - 21. 6. 1621) - physician, humanist and philosopher Slovak origin. One of the twenty-seven nobles were executed on the Old Town Square.

J�n Jesensk�, also known as Jessenius, was born in Breslau, but his family came from Central Slovakia Turks. Significant talent manifested in childhood, in just sixteen years he began studying medicine and philosophy in Germany Wittenberg, then continued at the universities of Leipzig and Padua, Italy. In August 1591 there defended his doctorate in medicine (file O diseases bile at the three-day fever ) and philosophy (rather radical work The right of the people to resist tyrants ). Because of evangelical religion to him, Catholic University of Padua title has not granted on the recommendation of his professors, however, won in Prague. After returning to his native Breslau, he opened a medical practice and soon became a renowned expert. Fame had opened the way for the then social elite: soon became the personal physician to the Elector of Saxony in Dresden. In 1594 he reappeared at the University of Wittenberg, where he became professor of surgery and anatomy and became dean of the medical faculty. In 1597 he was even elected rector of this important University.

Three years later came Jesenius to Prague where he visited his friend, the astronomer Tycho Brahe. In Re�kov� dorm conducted on the body of an executed man's first public autopsy in the Czech lands. This caused a very contradictory reactions. Professional public was thrilled that lay expressing indignant. The autopsy released later on wittenbergsk� university file called Prague Anatomy .

In 1602, the Jessenius at the request of Emperor Rudolf II. moved to Prague. He devoted himself to scientific and educational activities and later became the personal physician of Rudolf's brother and later Emperor Matthias. Followed by a period trips to various locations in Europe to in 1617 finally settled in Prague.

As a prominent figure was elected Rector of Charles University, which at the time was going bankrupt restore former glory. Carolinum was then the Habsburg important center of resistance and Jessenius as a Protestant, was one of its main leaders. To him after the Battle of White Mountain victorious Catholic party forgiven. Renowned physician and politician was thrown into prison, subjected to interrogation and, together with other twenty-six Czech noblemen sentenced to death. His head was to become alert, along with eleven other, hung at the Old Town Bridge Tower, where he allegedly stayed for ten years.