I assume you also include individual composers. Give some credit to the people not in the spotlight.
groups:
Sound Horizon
Gorillaz
The Beatles
Daft Punk
composers:
Revo
John William
Joe Hisaishi
Yoko Kanno
Yuji Ohno
Hiroyuki Sawano
Tom Jobim
vocalists:
Revo
Utada Hikaru
Mika Kobayashi
T. M. Revolution
Did I mention Revo who has a group called Sound Horizon?