To many to name. Just like other countries, and the brilliant music and talent that they give to the world.
There are too many to choose the most significant.
I suppose Elvis Presley in a way, but each decade has more than one and it would depend too on the genre preferred. Another is Gershwin, for example and then what about Philip Glass
What is the song that opens the Bugs Bunny and Tweety show?
Beyonce she's a quadruple threat
Bruce Springstein. His fake-*** blue collar bullsh!t aesthetic reminds me a lot of America in general.