Alois Hitler, Austrian civil servant (d. 1903)
Alois Hitler Sr. (born Alois Schicklgruber; 7 June 1837 – 3 January 1903) was an Austrian civil servant in the customs service, and the father of Adolf Hitler, dictator of Nazi Germany.

Alois Schicklgruber was born out of wedlock. His mother was Maria Schicklgruber, however his biological father remains a mystery. That uncertain parentage has led to claims that Alois' third wife, Klara (Adolf's mother), may have also been either Alois' first cousin once removed or his half-niece. Alois' unknown father also meant that Adolf Hitler himself could not prove the identity of his paternal grandfather was, and thus could not prove his own "Aryan descent" according to Nazi race laws. In 1876, Alois convinced the Austrian government to acknowledge his deceased stepfather Johann Georg Hiedler as his biological father. Alois then legally changed his last name to that of his stepfather. However during this process, the Austrian authorities misspelled his name as "Hitler" for unknown reasons. This meant that Klara was legally recognized as Alois' first cousin once removed.Adolf Hitler's parents met in 1876. While Alois was still married to his second wife, he began an affair with Klara, whom he hired as a household servant. Their relationship continued in secrecy until Alois' wife died and Klara became pregnant which prompted Alois to marry her in 1885. According to a close friend, Alois was "awfully rough" with his wife Klara and "hardly ever spoke a word to her at home". Alois treated his children with similar contempt and he often beat them.