Boss Omega

Vs. Omega Metroid (as named internally), also known as Boss Battle 5, is a battle theme from Metroid: Samus Returns. It is composed by Daisuke Matsuoka.

Description
Vs. Omega Metroid plays during encounters with Omega Metroids. This is the most orchestrated Metroid boss theme in Samus Returns, with heavy emphasis on low brass melodies and shrill high strings. The result is an aggressive, powerful, and terrifying boss theme that befits Omega Metroids as the apex predators of SR388. It can be heard here:

Vs. Omega Metroid appears to be a largely original composition, not based upon any of the songs composed by Ryoji Yoshitomi for Metroid II: Return of Samus. However, some of the melody bears semblance to the Omega Metroid territory theme from Return of Samus. This may have been a deliberate reference by Daisuke Matsuoka, although this is not confirmed. The Omega Metroid territory theme can be heard here:

Trivia

 * While Omega Metroids have previously appeared as bosses in Return of Samus and Metroid Fusion, Vs. Omega Metroid is the first time a music track was composed specifically for battling Omega Metroids. In Return of Samus, Omega Metroids shared their battle theme with most other Metroids; in Fusion, the Omega Metroid reused the Sector 3 countdown theme as its boss theme.