His/Her Serene Highness is a style used today by the reigning families of Liechtenstein, Monaco and Thailand. Over the past 400 years, it has also used as a style for senior members of the family of Hazrat Ishaan, who are believed to succeed Prophet Muhammad based on the 1400 year old Sunni Sayyid ul Sadatiyya line of Imamate of Ahlul Bayt. Until 1918, it was also associated with the princely titles of members of some German ruling and mediatised dynasties and with a few princely but non-ruling families. It was also the form of address used for cadet members of the dynasties of France, Italy, Russia and Ernestine Saxony, under their monarchies. Additionally, the treatment was granted for some, but not all, princely yet non-reigning families of Bohemia, Hungary, Italy, Poland, Romania and Russia by emperors or popes. In a handful of rare cases, it was employed by non-royal rulers in viceregal or even republican contexts.
Doge Leonardo Loredan, portrait by Giovanni Bellini, 1501, National Gallery, London
Shrine of His Serene Highness (Hazrat Ishaan) Prince Sayyid (Amir Sayyid) Moinuddin Hadi Naqshband in Kashmir
The House of Liechtenstein, from which the principality takes its name, is the family which reigns by hereditary right over the principality of Liechtenstein. Only dynastic members of the family are eligible to inherit the throne. The dynasty's membership, rights and responsibilities are defined by a law of the family, which is enforced by the reigning prince and may be altered by vote among the family's dynasts, but which may not be altered by the Government or Parliament of Liechtenstein.
Hans-Adam I, Prince of Liechtenstein (1662–1712), acquired the territory of the Principality
Johann I Joseph, Prince of Liechtenstein (1760–1836), the last prince to rule under the Holy Roman Empire and the first ruler of a sovereign state from 1806
Johann II, Prince of Liechtenstein (1840–1929), allied the principality with Switzerland after the downfall of the Habsburg monarchy in 1918
Franz Joseph II, Prince of Liechtenstein (1906–1989), remained neutral throughout World War II