The ancestors and relatives of Adolf Hitler have long been of interest to historians and genealogists because of the biological uncertainty of Hitler's paternal grandfather, as well as the family's inter-relationships and their psychological effect on Hitler during his childhood and later life.

Alois Schicklgruber (Adolf's father) changed his surname on 7 January 1877 to Hitler (derived from that of his deceased stepfather, Johann Georg Hiedler), which was the only form of the last name that his son Adolf used. Before Adolf Hitler's birth, his family used many variations of the family surname Hitler almost interchangeably. The common variants included Hiedler, Hüttler, Hytler, and Hittler.

Adolf Hitler's sister Paula, who died in 1960 and did not have children, was the last member of the family still bearing the Hitler surname on their tombstone. In 2025, it was reported that only five members of the Hitler family bloodline, all men who fathered no children, were still living. This figure does not include Hitler's maternal cousins, the Koppensteiners. Three of these descendants are sons of Adolf Hitler's nephew, William. William Hitler was not on good terms with Adolf Hitler, who referred to William as his "loathsome nephew". William was publicly critical of his uncle, fought with the United States Navy during World War II, and after WWII ended, changed his last name from Hitler to Stuart-Houston. None of William's sons, who all bear the last name Stuart-Houston, have had children of their own.

Etymology There are several different theories for the surname's origin and meaning.

The Austrian historian and social democratic politician Franz Jetzinger noted in his 1976 biography of Adolf Hitler that many Nazis asserted that the name Hitler derived from Hirt (meaning a herdsman) or Hüter (a guardian or protector), framing their Führer as the divinely-ordained "shepherd of all Germans." Jetzinger dismissed this explanation outright as "nonsense," acknowledging that Hirt could change into Hiater or Hieter but claiming that it simply never could evolve into Hitler. He likewise rejected the idea that Hütte (meaning hut) could have become Hüttler (in English, 'hutter') and thence Hitler as "clearly wrong," asserting that it could instead only evolve into Hüttner even though both derivations are attested.

According to Jetzinger, "no amount of ingenuity can provide the name, Hitler, with a plausible German derivation." Instead, he argued, the name is likely a Germanized corruption of the Czech Hidlar or Hidlarček (of which he does not give the etymology), pointing to a supposed 15th-century influx of Czech settlers in the Waldviertel region along with the historic influence of the Bohemian branch of the Knights Hospitaller over Spital near Weitra where Adolf Hitler's own family lived for generations.

Jetzinger's hypothesis was accepted by German historian Joachim Fest, who stated in his own biography of Hitler that "The name Hitler, Hiedler, or Hüttler is probably of Czech origin." Brigitte Hamann expressed that "that the name Hitler [...] may come from the Czech[s], is certainly possible" but "The most plausible interpretation is that the name comes from 'Hütte' (cottage), in other words, that it means 'Häusler," which is both an old term for [a] miner and denotes someone who lives in a small house. Thus among Hitler's known ancestors there is no one whose name indicates Czech origin." Ian Kershaw rejected the theory, stating "Jetzinger's claim that the name 'Hitler' was of Czech origin has been shown to rest on flimsy grounds. 'Hüttler', meaning cottager or smallholder, was not an uncommon name in Austria."

In a similar strain of thought to Jetzinger, the journalist and historian Konrad Heiden speculated about the surname possibly being Jewish in origin, writing in 1936: "The unusual and rather curious name of Hitler occurs more frequently among Eastern Jews than among Germans, and particularly in Galicia, Bukovina, Roumania and Poland." One such example is , a decorated Jewish Ukrainian Red Army soldier who fought in the Battles of Odessa and Sevastopol. "We are not justified, however," Heiden wrote, "in taking this as proof of a 'Jewish grandmother' of Adolf Hitler, no matter how many Abraham Hitlers, Herz Hitlers, or Esther Hitlers lived in Polna in Moravia and migrated thence to Vienna. No credible connection has so far been proved."

Such rumors of "subversive" Jewish origin, if true, would have been politically inconvenient for Adolf Hitler and the Nazi Party which preached Aryan racial supremacy. Thus, they proliferated in the anti-Nazi and sensationalist foreign press. Interest in Hitler's alleged Jewish and non-German ancestry was revived after World War II by the Frankenberger thesis, but has since been firmly discredited by historians, genealogists, and more recently geneticists.

According to German onomast , the surname might mean one who resides by a Hiedl, a term for a subterranean river or fountain in Austro-Bavarian dialects. corroborates the term Hied(e)l in his book Deutsche Namenkunde, describing it as an "occasionally drying spring," but proposes two separate origins and meanings of the Hitler surname: a 14th-century variation of Hüttler, meaning an overseer of the salt deposits of the River Salzach; and an 18th-century variation of Hiedler, meaning one who guards, descending from the Middle High German huot(e).

Family history The family is of Austrian German ethnicity.

Earliest family members The first known beginning of the Hitler family is with Stefan Hiedler (born 1672) and Agnes Capeller, whose grandson Martin Hiedler (17 November 1762 – 10 January 1829) married Anna Maria Göschl (23 August 1760 – 7 December 1854). This couple had at least three children: Lorenz (1800–1861), Johann Georg (baptised 28 February 1792 – 9 February 1857), and Johann Nepomuk (19 March 1807 – 17 September 1888). Johann Georg was the stepfather of Alois Schicklgruber (later Hitler), who was Adolf Hitler's father, and Johann Nepomuk was the future 's maternal great-grandfather. There is no additional information about Lorenz Hiedler. The Hiedlers were from Spital, a part of Weitra in Austria.

Johann Georg and Johann Nepomuk Brothers Johann Georg and Johann Nepomuk Hiedler are associated with Adolf Hitler in several ways, although the biological relationship is disputed.

Johann Georg was considered the officially accepted paternal grandfather of Hitler. Whether he was actually Hitler's biological paternal grandfather remains unknown. He married his first wife in 1824, but she died in childbirth five months later. In 1842, he married Maria Anna Schicklgruber (15 April 1795 – 7 January 1847) and became the legal stepfather to her illegitimate five-year-old son, Alois.

Around age 10, near the time of his mother's death, Alois went to live with Johann Nepomuk Hiedler (also known as Johann Nepomuk Hüttler) on his farm. Johann Nepomuk Hiedler became a relatively prosperous farmer and was married to Eva Maria Decker (1792–1873), who was fifteen years his senior. Johann Nepomuk Hiedler was named after Johann Nepomuk, a Bohemian saint for Bohemians of both German and Czech ethnicity. The Nazis issued a pamphlet during the 1932 second elections campaign titled "Facts and Lies about Hitler" which refuted the rumour spread by the Social Democrats and Centre Party that Hitler had Czech ancestors. There is no evidence that any of Hitler's ancestors were of Czech origin.

Father of Alois Hitler

The identity of the biological father of Alois is disputed. Legally, Johann Georg Hiedler, an itinerant miller, was the step-father of Alois Schicklgruber (later Alois Hitler), and Johann Georg's brother Johann Nepomuk Hiedler was therefore the step-uncle of Alois. Johann Nepomuk adopted Alois informally during Alois's childhood and raised him. It is possible that he was, in fact, the natural father of Alois but could not acknowledge this publicly due to his marriage. A perhaps simpler explanation is that he pitied the ten-year-old Alois after the death of the boy's mother Maria, as it could hardly have been a suitable life for a ten-year-old child to be raised by an itinerant miller. Johann Nepomuk died on 17 September 1888 and willed Alois a considerable portion of his life savings.

It was later claimed that Johann Georg had fathered Alois prior to his marriage to Maria. The claim that Johann Georg was the true father of Alois was not made during the lifetime of either Johann Georg or Maria. In 1877, 20 years after the death of Johann Georg and almost 30 years after the death of Maria, Alois was legally declared to have been Johann Georg's son. Johann Nepomuk arranged to change the surname of Alois to "Hitler" and to have Johann Georg declared the biological father of Alois in 1876. Johann Nepomuk collected three witnesses (his son-in-law and two others) who testified before a notary in Weitra that Johann Georg had several times stated in their presence that he was the actual father of Alois and wanted to make Alois his legitimate son and heir. The parish priest in Döllersheim, where the original birth certificate of Alois was kept, added Johann Georg's name to the birth register. Alois was 39 years old at the time and was well-known in the community as Alois Schicklgruber.

Accordingly, Johann Georg Hiedler is often cited as having possibly been the biological grandfather of Adolf Hitler. Although Alois was legitimized and Johann Georg Hiedler was considered the officially accepted paternal grandfather of Hitler by the Third Reich, whether he was Hitler's biological grandfather remains unknown, which has caused speculation. However, his case is considered the most plausible and widely accepted. Other speculations include Johann Nepomuk, and a Graz Jew by the name of Leopold Frankenberger, as rumored by the head of the General Government in Nazi-occupied Poland, Hans Frank, during the Nuremberg Trials. Historians have concluded that Frank's speculation has no factual support. Frank said that Maria came from "Leonding near Linz", when in fact she came from the hamlet of Strone's, near the village of Döllersheim. No evidence has been found that a "Frankenberger" lived in the area; the Jews were expelled from Styria (which includes Graz) during the 15th century and were not permitted to return until the 1860s, several decades after the birth of Alois.

Pölzl family Johanna Hiedler, the daughter of Johann Nepomuk and Eva Hiedler () was born on 19 January 1830 in Spital (part of Weitra) in the of Lower Austria. She lived her entire life there and was married to Johann Baptist Pölzl (1825–1901), a farmer and son of Johann Pölzl and Juliana (Walli) Pölzl. Johanna and Johann had five sons and six daughters, of whom two sons and three daughters survived into adulthood, the daughters being Klara, Johanna, and Theresia. Klara's brothers' identities are unknown.

1870s

At the age of 36, Alois Hitler was married for the first time, to Anna Glasl-Hörer ( Glasl), the 50-year-old adopted daughter of a wealthy customs official. She had an illegitimate son named Josef Glasl-Hörer, born on 16 October 1851 in Radstadt. Anna was sick when Alois married her and was either an invalid or became one soon afterwards. Not long after the wedding, Alois Hitler began an affair with 19-year-old Franziska "Fanni" Matzelsberger, one of the young female servants employed at the Pommer Inn, house no. 219, in the town of Braunau am Inn, where he was renting the top floor as a lodging. Bradley Smith states that Alois had numerous affairs during the 1870s, resulting in his wife initiating legal action. On 7 November 1880, Alois and Anna separated by mutual agreement. Franziska Matzelsberger became the 43-year-old Hitler's girlfriend, but the two could not marry since by Roman Catholic canon law, divorce is not permitted.

1880s