I was going to mention Mohorovičić [1], but it turns out he was Croatian (which to me means that Milanković and Mohorovičić were both Yugoslavians, but the Serbs and the Croats don't seem to view things that way).
Then I remembered the Serbian-American inventor/engineer Michael (or Mihajlo) Pupin [2], who really deserves to be better known. Besides being an inventor, he won a Pulitzer prize in 1924 for his autobiography, "From Immigrant to Inventor". Anyway, that's the main reason I'm posting this comment, to attempt to rescue Pupin from semi-obscurity.
But while I'm here, I'll mention that I didn't learn about Milankovitch cycles in astronomy courses, but in geology courses, because of the cycles' influence on the timing of the Ice Ages.
[1] https://en.wikipedia.org/wiki/Andrija_Mohorovi%C4%8Di%C4%87