Hans-Adam II (Johannes Adam Ferdinand Alois Josef Maria Marco d'Aviano Pius; born 14 February 1945) is the Prince of Liechtenstein, reigning since 1989. He is the son of Prince Franz Joseph II and his wife, Countess Georgina von Wilczek. He also bears the titles Duke of Troppau and Jägerndorf, and Count of Rietberg. Under his reign, a 2003 constitutional referendum expanded the powers of the Prince of Liechtenstein. In 2004, Hans-Adam transferred day-to-day governmental duties to his eldest son Hereditary Prince Alois as regent, as his father had done to him in 1984 to prepare him for the role of Prince.

He was born on 14 February 1945 in Zürich, Switzerland, as the eldest son of Prince Franz Joseph II and Princess Gina of Liechtenstein, with his godfather being Pope Pius XII. His father had succeeded as Prince of Liechtenstein in 1938 upon the death of his childless grand-uncle, Prince Franz I, and Hans-Adam was thus hereditary prince from birth.

In 1956, he entered the Schottengymnasium in Vienna. In 1960, he transferred to the Lyceum Alpinium Zuoz in Switzerland, earning a Swiss Matura and a German Abitur in 1965. He then worked as a bank trainee in London before enrolling at the University of St. Gallen to study business administration, graduating with a licentiate in 1969. He is fluent in English and French in addition to his native German.

In 1984, Prince Franz Joseph II, while legally remaining head of state and retaining the title of sovereign prince, formally handed the power of making day-to-day governmental decisions to his eldest son as a way of beginning a dynastic transition to a new generation. Hans-Adam formally succeeded as Prince of Liechtenstein upon the death of his father on 13 November 1989.

A referendum to adopt Hans-Adam's revision of the Constitution of Liechtenstein to expand his powers passed in 2003. The prince had threatened to abdicate and leave the country if the referendum did not result in his favour.

On August 15, 2004, Hans-Adam formally handed the power of making day-to-day governmental decisions to his eldest son Hereditary Prince Alois as regent, as a way of beginning a dynastic transition to a new generation. Legally, Hans-Adam remains the head of state. Hans-Adam's father Franz Joseph II had similarly done so for him on 26 August 1984.

In a July 2012 referendum, the people of Liechtenstein overwhelmingly rejected a proposal to curtail the political power of the princely family. A few days before the vote, Hereditary Prince Alois announced he would veto any relaxing of the ban on abortion, also up for referendum. 76 per cent of those voting in the first referendum supported Alois' power to veto the outcome of future referendums. Legislators, who serve on a part-time basis, rose in the hereditary prince's defence on 23 May, voting 18 to 7 against the citizens' initiative.

Throughout his reign, Hans-Adam has been a prominent proponent of strengthening Liechtenstein's economic and political independence from Switzerland, with which Liechtenstein has been in a customs union since 1924. In a speech from 1970 nicknamed the "backpack speech", Hans-Adam declared his intentions to push for an independent Liechtenstein foreign policy. He was a major proponent of Liechtenstein joining the United Nations, which the country successfully did in 1990.