Von Schmidt auf Altenstadt, (also von) was a German noble family whose seat was at Schloss Gattendorf outside Hof, Bavaria near the Czech border. Also known as Schmidt von Altenstadt, it had branches in other countries including the Netherlands, and Russia, where its members also distinguished themselves. In 1861, one branch received a baronial title from the King of Württemberg.
Johann Fabricius, originally surnamed Schmidt, had altered his name to the Latin form "Fabricius", in order to attract the attention of the Emperor. He served Maximilian II against the Turks and was given a coat of arms by the imperial Letters Patent of 2 November 1564. His son Martin was ennobled on 10 December 1577. They were granted a swan coat-of-arms where the swan is in an attack position on the shield; this is repeated in miniature "above the crown".
In 1638 the Fabricius family reverted to their former surname of Schmidt and on 23 February 1713 were granted the additive "auf Altenstadt". The native city of the family was Hof but they had a village called Schmidt where there was a castle called Burg Hengebach four miles away from the town of Heimbach.
On 18 October 1712/23 February 1713 the Emperor Charles VI granted augmentation of a knight's arm holding a sword to the swan coat-of-arms, to heirs Anton Johann Christoph, Johann Georg, and Christopher Wolf (successive lords of Gattendorf). The three brothers succeeded each other, one after the other, as lords of Gattendorf; the first two died without heirs. The third brother had children and the line continued.
Hans-Georg Schmidt von Altenstadt (21 August 1904 − 25 July 1944) was the last baron von Altenstadt of the castle Schloss Gattendorf and the last in life of the aristocratic family Von Schmidt auf Altenstadt. He reached the rank of Generalmajor 1 July 1944. He was married to the former Lillian Thordsen with whom he had three daughters. As there was no son and heir the baronial line of Schmidt von Altenstadt became extinct in 1944. Although the family is officially extinct, genetic connections to the family are still to be found in the United States and England. A direct descendant from Johann Schmidt/Fabricius exists within the UK.