The original Halo took the FPS console world by storm in November of 2001. Since then it’s spawned numerous sequels and generated hundreds of millions of dollars. But through it all, I still think the original theme music from the first game is the best. Here is the original in all its orchestral and choral glory.
Violinist Lindsey Sterling has quite the following on Youtube and she’s covered a lot of different stuff. Here’s her version of the theme with William Joseph on piano.