One of the Noble Families of the First Terran Empire.
The ancestors of House Adelhardt appear to have been minor nobles of Carinthia, or perhaps southern Bavaria, in the thirteenth century CE. By the fifteenth century, this family had become associated with the House of Habsburg.
Adelhardt ancestors served the Habsburgs until World War I -- at that time one Adelhardt ancestor was sneaked out of Austria, along with his family; he changed the family name to "Adelhardt" and took up residence in the United States.
Derek David Adelhardt, Sr. (1928 - 1953 CE) managed, by investing in the stock market, to build up a respectable fortune. When he died in a minor war in Korea, he passed this fortune on to his son, Derek David Adelhardt, Jr., and his daughter, Marie Adelhardt. Marie proved a financial genius. She managed to keep the family fortune intact through the economic chaos of the 1970's, and invested heavily in the fledgling computer industry of the 1980's. Her nephew, Roger Adelhardt, Sr. (1978 - 2023 CE), was one of the founding members of the Nexus.
Roger Adelhardt, Jr. (2003 - 2082 CE) continued his father's Nexus work, and in 2042 he had a seat on the Terran Council.
Lewis Adelhardt (2031 - 2082 CE) was a delegate to the Terran Council; he also invested a large amount of the family fortune in the Leikeis Colony. This investment returned many times over during the following decades, as well as guaranteeing House Adelhardt control of at least part of Leikeis.
Lewis' son Gerald Adelhardt (2063 - 2144 CE) founded Dunsinane for his family and built Castle Adelhardt. (Since then, one member of the Family has been the Planetary Administrator, inevitably titled "Thane of Cawdor.") Meanwhile, Gerald's sister Lady Frieda Adelhardt (2066 - 2152 CE) distinguished herself as Ambassador from Terra to Leikeis, and later the first Exchequer of Leikeis.
By the time the Empire was founded in 2153 CE, House Adelhardt was an integral part of the ruling nobility.