I Googled The Empire Strikes Back to see what everyone was saying about the 30th anniversary and found this posted by Jedi Grrrl on Tumblr --
played Rebel Force Major Derlin in ESB
he was born on April 6th 1947
his most recognizable role is “Cliff” from Cheers
he is the only actor to voice a character in all the Pixar movies - Toy Story (1, 2 & 3), A Bug’s Life, Monsters Inc, Finding Nemo, The Incredibles, Cars, Ratatoullie, Up, Wall-E
Interesting Tidbit: The trading card for his Star Wars: Episode V - The Empire Strikes Back (1980) character, Bren Derlin, says that “At the Mos Eisley Cantina, everybody knows his name.” Derlin is never seen in the Mos Eisley Cantina. This is an inside joke about his character Cliff Clavin the mailman, who frequents Cheers, “where everybody knows your name”
From Wookieepedia --
In the Star Wars Customizable Card Game, Derlin's card notes "At the Mos Eisley Cantina, everybody knows his name." The line is a reference to the theme song of Cheers, in which Ratzenberger appeared as "Cliff Clavin."
I already knew that John Ratzenberger was in ESB, but I found the quote from the trading card interesting. Unfortunately, I couldn't find a scan of it.