This article investigates whether and how five of the major metal subgenres differ in their harmonic practices in the twenty-first century. One hundred metal tracks – twenty from each of the five subgenres of power metal, black metal, metalcore, melodic death metal and progressive metal – released since 2000 were analysed, capturing their chord progressions and modulation techniques. Tonal analysis indicated that although each subgenre seems to adopt the techniques used by the early heavy metal bands of the 1970s and 1980s, individual signature styles contribute to the desired sonic aesthetic. The study found pronounced harmonic practices in most subgenres, yet the most distinctive in power metal and black metal. While black metal focused on non-diatonic minor chords for a dark atmosphere and dissonant aesthetic, power metal emphasized the brighter Dorian mode and employed baroque and classically influenced secondary dominants and diminished seventh chords to add colour to progressions and brighten the sound.