Zeal & Ardor is a Swiss avant-garde metal band started and led by Manuel Gagneux, a Swiss-American musician who had previously created a chamber pop project called Birdmask.

Initially a solo project, the band signed with MVKA Records in 2016 and expanded to a full lineup, with Gagneux on vocals and guitar, backing vocalists Denis Wagner and Marc Obrist, guitarist Tiziano Volante, bassist Mia Rafaela Dieu, drummer Marco Von Allmen.

[16] After moving to New York City in 2012, Gagneux started Birdmask, a chamber pop project.

[13][note 1] Gagneux posted his Birdmask music to 4chan "to get feedback because they're brutally honest and don't give a shit about you".

[20] He would ask users for two musical genres to combine and create a song in half an hour as an experiment to expand his creativity.

[22][23] Other genres suggested included "Afro Djent, Nashville Power Electronics and Industrial Grunge".

[27][better source needed] Gagneux self-released the demo album Zeal and Ardor to Bandcamp in June 2014.

In 2017, the project became a full-fledged band with the addition of backing vocalists Denis Wagner and Marc Obrist, guitarist Tiziano Volante, bassist Mia Rafaela Dieu, and drummer Marco Von Allmen.

[37][38] Gagneux formed the full band after promoter Walter Hoeijmakers asked him to play at the Roadburn Festival.

Using the rich heritage and culture as a part of my musical identity it felt like cowardice to sit by and continue with my routine as if nothing happened.

This record is for Michael Brown, Eric Garner, George Floyd and the countless untold and nameless killed.

[63] During the later part of the 2019 tour, bassist Mia Rafaela Dieu missed several shows due to gastroparesis caused by Ehlers-Danlos syndrome.

Devil Is Fine features elements of soul,[83] black metal,[5] Delta Blues,[84] folk, gospel as well as jazz and lo-fi influences.

[89] Zeal & Ardor retains many elements of the previous albums including industrial metal and blackgaze influences.

[90] The band is influenced by artists such as Mayhem, Burzum, Darkthrone, Wendy Carlos,[16] Tom Waits,[24] Golem, Portishead, Naglfar, and Iron Maiden,[91] as well as nu-metal bands such as Deftones and Limp Bizkit, who Gagneux states are his "guilty pleasures".

[93] -Most Zeal & Ardor releases feature Von Allmen on drums with Gagneux performing every other instrument, until 2024's Greif which was written and recorded as a full band.