Cheers is an American sitcom that ran for eleven seasons (and 271 episodes) between 1982 and 1993. Frasier is a spin-off of Cheers. The first appearance of Dr. Frasier Crane is in Season 3 of Cheers, as a love interest for Diane Chambers, his erstwhile patient.
Other characters from Cheers have made appearances in the Frasier storyarc. In the Frasier season-two episode The Show Where Sam Shows Up, when Sam meets Martin, Frasier explains that at the time, he was angry after an argument with his father on the phone. However, in The Show Where Woody Shows Up, when meeting Martin, Woody says he remembers hearing about him.
In the ninth-season episode of Frasier, "Cheerful Goodbyes" in 2002, Frasier returns to Boston to give a speech and Niles, Daphne, and Martin come along to see the city. Frasier runs into Cliff Clavin (played by John Ratzenberger) at the airport and learns that Cliff is retiring and moving to Florida. Frasier and company attend Cliff's retirement party, where Frasier reunites with the rest of the gang from Cheers (minus Sam, Woody, and Rebecca), including bar regular Norm Peterson (played by George Wendt), waitress Carla Tortelli (played by Rhea Perlman), barflies Paul Krapence (played by Paul Willson) and Phil (played by Philip Perlman), and Cliff's old post-office nemesis Walt Twitchell (played by Raye Birk).