Boss Zeta

Vs. Zeta Metroid (as named internally), also known as Boss Battle 4, is a battle theme from Metroid: Samus Returns. It is composed by Daisuke Matsuoka.

Description
Vs. Zeta Metroid plays during encounters with Zeta Metroids. It opens with a shrill stinger, followed by a low choir reminiscent of the Chozo temple themes from Metroid Prime and Metroid: Zero Mission. The rest of the track is an exciting high-energy battle theme, with a more cinematic flair compared to Vs. Alpha Metroid and Vs. Gamma Metroid due to featuring an dramatic brass melody in lieu of the standard electronic synths. It can be heard here:

Vs. Zeta 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, the opening stinger is notably similar to the original Metroid battle theme from Return of Samus. This may have been a deliberate reference by Daisuke Matsuoka, although this is not confirmed. The original Metroid theme can be heard here: