Alexander von Humboldt might be a good candidate. He may not have been considered a "genius" (in his preferred field, which happened to be geology) so much as a "polymath", but since the specialization of scholarship only really took off around the turn of the 19th/20th century, that is almost to be expected.

In terms of being a household name and general recognition as an outstanding Universalgelehrter, he definitely fits the bill. Especially in South America, there are COUNTLESS places named after him, but he also left a serious mark in the U.S. (where he had the trust and respect of presidents), and was of course extremely well known in his native Europe. As with Einstein, whom we all intuitively consider as "our Einstein" irrespective of the country we come from, von Humboldt similarly transcended national borders (if in the different context of the long end of 18th century cabinet policy, as it gave way to 19th century nationalism), and thus was a courtier at the Prussian court yet still got away with living in Paris for years at a time (not to mention his - less successful - endeavors in London, and of course his copious traveling around the globe).

I don't know the background behind the choice to name Carl Sagan's popsci/educational TV series "Cosmos", but it may be a nod to von Humboldt's sprawling multi-volume multi-disciplinary "(not-so-)brief introduction to everything" which he named Kosmos, and which was HUGE in his day. A European-wide bestseller.