The Players' Guide to the Cities/Enemy Groups

There are dozens of gangs, criminal cartels, paramilitary groups, law enforcement organizations, and mystic orders at work throughout Paragon City and the Rogue Isles. Be aware that your enemies will have ranks within their organization. Minions are line troops, lieutenants are officers, and bosses are commanders. Be much more cautious of lieutenants and especially bosses than you would be with a minion of the same consideration color. Leaders tend to have abilities that make them particularly dangerous.

A comprehensive list of all the various factions in the game can be found here.