Which is the most influential heavy metal band and why?

The most influential heavy metal band is arguably Black Sabbath. Formed in Birmingham, England in 1968, Black Sabbath is considered the pioneers of heavy metal music. Their self-titled debut album, released in 1970, is widely regarded as the first heavy metal album. Black Sabbath's dark and heavy sound, characterized by Tony Iommi's distinctive guitar riffs and Ozzy Osbourne's powerful vocals, laid the foundation for the genre. The band's music has influenced numerous subsequent heavy metal bands, including Metallica, Slayer, and Megadeth. Black Sabbath's impact on heavy metal music can also be seen in their lyrics, which often deal with themes of darkness, occultism, and social issues. The band's influence has been acknowledged by many musicians and critics, and they are often considered one of the most important and influential bands in rock history.