The Halo theme originated with Halo: Combat Evolved in 2001 and became one of the most recognizable pieces of video game music. Composed by Martin O'Donnell and Michael Salvatori, its chant-like opening helped define the series' identity. Short clips of the theme spread widely through gaming forums, YouTube edits and meme videos because the music instantly signals epic stakes, sci-fi grandeur and old-school Xbox nostalgia. It still shows up whenever creators want a moment to feel heroic, reverent or humorously overblown.