I'm surprised about the lack of classical music in this thread.
Brahms's lullaby.
Strauss's Blue Danube.
Tchaikovsky's 1812 Overture.
Bach's (although disputed) Toccata and Fugue in D minor.
Händel's Hallelujah chorus from the Messiah.
Bizet's Toreador song.
Fucik's Entry Of The Gladiators.
Beethoven's Moonlight Sonata 1st movement.
Grieg's In The Hall Of The Mountain King from the Peer Gynt suite.
Orff's O Fortuna from Carmina Burana.
Strauss's Also Sprach Zarathustra.
Tchaikovsky's Dance Of The Sugar-Plum Fairy.
Wagner's Ride Of The Valkyries.
Chopin's Funeral March from Sonata no. 2.
Bizet's Habanera from Carmen.
And many more.
Or a national anthem, American probably.
Dude what? I have no idea what the American national Anthem is.
This. The American anthem really isn't that well known in other countries.