There are currently a few bands with the name avantgarde, regardless of how it is actually spelt. One well‑known band is an indie rock band from Spain http://en.wikipedia.org/wiki/Avantgarde_(band) and another is a booming rock band from Brunei.

Brunei's Avantgarde consists of Syaeful (vocals, songwriter, composer), Sofi (drums), Yus (guitar), Erul (guitar) and Jeff (bass). Avantgarde's music style is rock, close to nu metal, and Syaeful sings with normal and screaming voices. To date they have 8 singles and are going to release an EP album that compiles all their songs locally, with plans to record a full length album.