The Mediatized Houses (Standesherrlichte Häuser)) were ruling princely and comital-ranked houses which were mediatized in the Holy Roman Empire during the period of 1806–15 as part of the German Mediatization, and were later recognised in 1825-29 by the German ruling houses as possessing considerable rights and rank. With few exceptions, these houses were those whose heads held a seat in the Imperial Diet when mediatized during the establishment of the Confederation of the Rhine in 1806–07 by France in 1810, or by the Congress of Vienna in 1814–15. The Mediatised Houses were organised into two ranks: the Princely houses predicated with Serene Highness, which previously possessed a vote in the Bench of Princes; and the Comital houses predicated with Illustrious Highness, which previously possessed a vote in one of the four Benches of Counts. Whilst mediatization occurred in other countries such as France, Italy and Russia, only the certain houses within the former Holy Roman Empire comprised the Mediatized Houses.
Mediatized houses generally possessed greater rights than other houses. Whilst they lost sovereignty and certain rights (such as legislation, taxation, final jurisdiction, and control over policing and conscription) over their territories, they still often retained their private estates and feudal rights, which may have included rights over forestry, fishing, mining, hunting, jurisdiction over policing, and lower jurisdiction over civil and criminal court cases. Mediatised Houses also possessed the right to settle anywhere within the German Confederation. The Congress of Vienna specified that the Mediatised Houses were recognised as the first vassals in their respective states, and were equal in rank to the ruling houses. However the Congress of Vienna did not specify which houses were considered mediatised.
Mediatised sovereign houses possessed a rank higher than other aristocratic houses of equal or higher rank, within the princely or comital rank they possessed. For example, a Prince of a mediatized house ranked higher than a Duke of a house that never possessed immediacy, even though nominally a duke is of a higher rank than a prince. In effect, this gave the mediatised Princely houses the same rank as the sovereign houses of Europe. This had practical effects in determining whether a marriage was considered morganatic or not and the rights the children of such a marriage would possess.
It was ultimately left up to each of the sovereign states to determine which families were counted as part of the Mediatized Houses and which were not, leading to discrepancies between the roster of the Imperial Diet in 1806 and the houses counted amongst the Mediatized houses. Prior to 1806, the term "exemption" was used to refer to states which surrendered their immediacy and high jurisdiction rights to another state but retained their votes in the Imperial Diet. Not all exempt houses were counted amongst the Mediatized Houses. Further discrepancies exist because the houses were mediatized between 1806–14 and the rosters of the Princely and Comital mediatized houses were not drawn up until 1825 and 1829 respectively, during which period some families had become extinct or divested their mediate rights to the territories in question.
From 1836 the Almanach de Gotha began listing the Mediatised Houses in a separate category to both the ruling houses of Europe, and the lower nobility.
The rights of the Mediatised Houses in Austria and Czechoslovakia were abolished in 1919 following the defeat of Austria-Hungary in World War I and the establishment of republics in those countries. Rights were also abolished in Germany in 1919, however the abolition was not enforced.
- The Princely House of Castell-Castell
- The Princely House of Castell-Rüdenhausen
- The Comital House of Neipperg