Vampire squid refers to any large private or public organization that is a major drain on society through malicious but subtle or invisible actions. These organizations usually get away with what they do because of corruption within the society's regulatory structure.
"The world's most powerful investment bank Goldman Sachs
is a great vampire squid wrapped around the face of humanity, relentlessly jamming its blood funnel into anything that smells like money."
- Matt Taibbi, Rolling Stone, "The Feds vs. Goldman Sachs", 2009
The military industrial complex is like a vampire squid that is sucking the capital out of the pockets of the average American.