Let's focus...
The question was not intended to be, "What airlines occupy a terminal in its entirety." My question should read, "What airlines had terminals specifically built for their specifications?"
For example, while UA does occupy terminals (6), 7 and 8 at LAX, those terminals are "run of the mill." Other than a bit of interior decorating, they are the same as any other LAX terminals. Same goes for AA/DL at DFW, and DL in ATL.
But UA at ORD is unique, as are the original terminals at JFK.