@globalistas said:

I'm not a native speaker but I found Murphy's Oppenheimer character difficult to take seriously due to the awkward accent. Did Oppenheimer have this distincly non-American accent?

Thanks!

Robert Oppenheimer's father was a German-Jewish immigrant. His mother's father (Robert's grandfather) was also a German-Jewish immigrant, but she was born in New York, USA, and spoke American English. They were part of the American high society. Robert's father had learned British English from an Oxford tutor and most of his German accent was replaced with an Oxonian one. At home they spoke only English and Robert learned German from study.

Cillian Murphy (who plays Oppenheimer) is an Irish actor, who has done convincing American and Brummie (Birmingham) accents in movies and television.

Compare accent:

. J. Robert Oppenheimer

. Cillian Murphy as Oppenheimer

. Cillian Murphy as himself