The Many are a species with a collective conciousness. They are designed to... "harvest" humans, and add their tissue to the biomass, so that new organisms may be created. They're like the Zerg, but creepier.
The Many were created by SHODAN an artificial inyelligence who went mad, and saw herself as a goddess.
Your friends, who you deem dead, are not.
They sing in our symphony of life."