Here is a list of some of the organizations from the DC, Marvel and Image Comics Universes.
Advanced Idea Mechanics – AIM
Alliance of Evil
Alpha Fight
Defenders
Elders of the Universe
Exemplars
Fantastic Four
Galactus
Genosha
Green Lantern Corps
Hellfire Club
Hydra
Justice Society of America
Legion of Superheroes
New Warriors
Night Shift
S.H.I.E.L.D.
Serpent Society
Teen Titans
The Avengers
The Outsiders
ULTIMATUM
X-Men
