Surely the last name Hitler was around before Adolf, even if not directly related. I mean my last name is fairly common in the US, but I'm not related to most of them. I'm just curious if Hitler was a fairly common last name in Germany, and if that names usage decreased after WW2.
As they say, there's always more to say about a given topic, but you'll probably be interested in this answer by u/commiespaceinvader covering more or less the same question.
What happened to other people with the surname Hitler with the end of WWII?