There are at least 5 artists with this name:

1) Skatepunk band from Chile (2003-2009 / Reformed in 2023).
2) Metal band from the USA.
3) Dutch Power Electronics, side project of Terg and Cultus.
4) Hardcore band from Helsinki, Finland
5) Four piece Latinx queer band from Atlanta who formed in 2016.

1) A 4-piece skatepunk band formed in Chile back in 2003, Bitter has been reborn in 2023. Playing melodic and technical punk, they released the full-lengh "Desde Las Cenizas" in early 2024. Spotify: https://open.spotify.com/intl-es/artist/5wf69CJtjQJ5ppStlgIEFb?si=ZwLZL5-rRGqJ2VnLr-9W6A

2) Bitter is a popular metal band in the USA signed to No Explanation Records.
www.noexplanationrecords.com/epk/bitter/

Known for their powerful live performances the band released their 2nd album Headcase worldwide on No Explanation Records 11/2009
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Artist biography from last.fm