Before Cheers, there was a TV show about a bar. I don’t remember the name of the show or the bar. I thought it was something like Kessler’s, but I don’t see that in imdb.
I got here too late to give the right answer, which was the first thing I thought of when I read the thread title.
it starred Gabriel Dell, who was well-known before this as one of the Dead End Kids/east Side Kids/Bowery boys in, first, the movie Dead End and its sequels, then in a few series produced by various mostly poverty-row studios, making almost fifty of these films. After that, unlike many of his Bowery Boy alumni, he continued to act, showing up in a lot of unexpected places. He’s rumored to be the original voice of Boba Fett in The Star Wars Holiday Special. He was only 68 when he died in 1988.
Huntz hall, who was in the various kids series from the very start (and was most famous as Horace Debussy “Sach” Jones) made an appearance in the Corner Bar.
One of the things which I found out in the WIKI, it had the first gay character in a TV series. There are only production stills from the series online, I don’t see any video of it anywhere.