TOP 10: most memorable evil organization of the games

Alliance Halfa

Cerberus:Mass Effect
Templar:Assassin's Creed

Umbrella: Resident Evil
Terrorists: Postal 2 (even vegans, rednecks, haters RWS, haters of books)
The Enclave, Fallout

Cerberus (Mass Effect)
Dominion (StarCraft 2)
Hyperion (Borderlands 2)

Evil Genius is its own organization.

KOTOR - the Sith

1) Cerberus from Mass Effect;
2) Hyperion from Borderlands 2;
3) Umbrella from Resident Evil.

1) Cerberus from Mass Effect
2) Hyperion from Borderlands 2

Enclave - Fallout 2,3
Dark Brotherhood - The Elder Scrools

1) Umbrella - Resident Evil;
2) Alpha Sections - Beyond Good & Evil.

Abstergo, Cerberus, CELL from Crysis 2,3.

The entire top can be filled from the Deus Ex:

- Page Industries (including Versalife)
- The Illuminati (including the Majestic 12, although they then split)
- Lobster from DE:IW

PS: the Mechanists from Thief 2, I think

Umbrella - Resident Evil
Cerberus - Mass Effect
The Alliance Of Half-Life 2

UAC - DOOM
Nihon - Heroes of might and Magic 3

1) the Enclave
2) Cerberus
3) the knights Templar

1. Tallarini (Starcraft 2)
2. Dominion (Starcraft 2)
3. The pirates (Space Rangers 2)

1) Cerberus from Mass Effect
2) Umbrella from Resident Evil

Cerberus from Mass Effect

Still remembered the Aldmeri dominion

Sith, Cerberus, Templar