Maria Skłodowska-Curie was very helpful, at trying to solve #2 and #5 countries (by population) in one stroke. Good that the big 5 EU countries were simple enough to cover.

But why are a Greek-American, and an - unknown to the majority of Europeans - Austrian in there?

How many counties more populous than Austria are unrepresented? Do all EU countries count, or just EZ? (Poland is not EZ, is represented, still complained)

It's an impossible list. Europeans don't necessarily have shared heroes, and if they did, some of these wouldn't be top 6.