I couldn't think of a better sub to ask this, but I'm assuming before WWll there were many Hitler families in Austria maybe or Germany. Are there people who still have it as their last name? If not, which last name did Hitler's family adopted after his defeat? Are there any know descendants of his relatives (even if not close ones)?
This older answer should be of interest to you.
The name of Hitler’s father was Alois Schickelgruber, He was the illegitimate son of Johann Georg Hiedler, Nine years after Hiedler’s death Alois was declared a legitimate son. While changing his name Alois decided that his name should be Hitler. Why? I am just guessing: Alois was 39 years old when he changed his name. When you hear the name Schickelgruber in Austria the first guess would be that the person comes from Upper Austria. On the other hand if you speak the name Hiedler in Austria it would sound like Hidla. The e after the i just indicates that you accentuate the i. And that sounds very Czech. Alois was also not an uncommon name for Czechs in the 19th century. So Alois Schickelgruber as a proud German civil servant maybe have thought that Hitler had a better tone. When Adolf became famous there where a lot of rumors that he was of Czech origin.
The names Schickelgruber, Hitter, Hütter, Hiedler and other derivatives are still in use today. If there was someone with the name Hitler unrelated to Alois and Adolf he would have changed the name after the war, I presume.