Al Rosen was born 9 May, 1910, in Maryland.
He had a few uncredited roles in the 1940s in movies, including "Footlight Fever", "Without Reservations", and "The Stratton Story". According to Ken Levine's blog, he was a wrestler on TV in the 1950s.
In the 1970s, he worked as a production supervisor for "What's My Line?".
In 1980, he had a small role in the movie "Oh God!, Book II". On "Taxi", he appeared as a cab driver.
He played Al, a background barfly on Cheers. He was seen in over seventy episodes. Al was one of the most popular of the background characters. His first line ("Sinatra!") in "Fortune and Men's Weight" earned a big laugh, and he kept getting a line or two in episodes.
Aside from his Cheers role, he also had a bit recurring role on "Night Court", and had a guest role on "L.A. Law".
He passed away of cancer on 2 August, 1990. The Season 9 episode, "Norm and Cliff's Excellent Adventure" was dedicated to him. Cheers producer Cheri Eichen said of him: "He had the best batting average on TV - every time he'd open his mouth, he'd get a laugh."