The universe of characters centered around the fictional Dr. Frasier Crane. This character appeared on "Cheers," "Wings," and the eponymous sictom "Frasier." Any characters from these shows, and therefore any additional shows in which those characters appeared or were referenced in, are within this fictional reality.
"I know Lowell Mather (Thomas Haden Church) never actually met Sam Malone (Ted Danson), but they could have; all existed for years within the Frasierverse."
by President Warren G. Harding May 20, 2007