The Think-Tanks are the main antagonists of Old World Blues, the third expansion for Fallout: New Vegas. They consist of a team of scientists who were working at a top–secret experimental facility hidden inside a mountain called Big Mountain (a.k.a. Big MT or Big Empty) since before the Great War. The members are Dr. Klein (the leader), Dr. Mobius, Dr. Borous, Dr. Dala, Dr. 0 and Dr. 8. These were not their birth names, rather they adopted these names when they became robots, and all of them mean "infinity" in some way.