Sonic x Helluva Boss: Villains
Sonic's Universe:
The End(sonic Frontiers)
Dark Gaia
The Time Eater
Deadly Six
Dr. Starline
Mephiles the Dark
Infinite
Sage
Kitsunami
Surge
Helluva/Hazbin's Universe:
Adam
Lute
Valentino
Velvette
Vox
Stella
Paimon
Striker
Crimson
Andrealphus
Helsa von Eldritch
Exorcists
Baxter
Sir Pentious
Mammon
Seviathan von Eldritch
more villains in the future