This phrase in turn refers to the impression by many of Wagner's Der Ring des Nibelungen (aka the Ring cycle) as a lengthy opera finally concluding in an aria sung by a heavy-set woman dressed like a valkyrie. The Ring cycle is a set of four separate operas (lasting about 15 hours), in which the final scene includes Brünnhilde singing, and then riding onto Siegfried's funeral pyre. The set collapses and the entire cycle ends up in the Rhine river, where it started. The "fat lady" is often illustrated with a horned helmet, a spear, possibly a shield, and possibly blond braids.
The phrase has also been attributed to former major league manager Earl Weaver.
Despite his obvious allegiance to the Red Raiders, Texas Tech sports information director Ralph Carpenter was the picture of professional objectivity when the Aggies rallied for a 72-72 tie late in the SWC tournament finals. "Hey, Ralph," said Bill Morgan, "this... is going to be a tight one after all." "Right," said Ralph. "The opera ain’t over until the fat lady sings."
In the same newspaper on 26 November 2006, Steve Blow followed up the discovery by contacting Bill Morgan about the incident: "Bill vividly remembers the comment and the uproar it caused throughout the press box. He always assumed it was coined on the spot. 'Oh, yeah, it was vintage Carpenter. He was one of the world’s funniest guys,' said Bill, a contender for that title himself."
A suggestion that the phrase is older is based on an old saying in the Southern United States stating that "Church ain't over until the fat lady sings". This form of the line was apparently well known in the South for years, appearing in a 28 page booklet in 1976 entitled Southern Words and Sayings.
Kate Smith for whom Irving Berlin wrote "God Bless America", was a star of radio in the nineteen thirties who continued as a popular performer with her own show on NBC in the early days of television. Her song "When The Moon Comes Over the Mountain" was featured during her television years in the 1950s to close the broadcast night on her network, preceding the National Anthem and the broadcast pattern.
In her years as a radio personality her physical appearance was unknown to many of her listeners, but it was a fact that couldn't be ignored when she later appeared on television. She was both beloved and the brunt of more than a few jokes.
Many children of the fifties remember staying up that late, and well remember that the broadcast night was not over until after that particular fat lady sang. Some will claim that its appearance in writing and the credit to Dan Cook as the originator of the expression is exaggerated and that Kate Smith was specifically the Fat Lady alluded to from an aural tradition dating to twenty years before. These will say that the expression enjoyed a long use based on a cruel comment, and that Dan Cook changed the words which are still in use to the "The opera ain't over" to claim credit for it - or perhaps to obfuscate its true origin.
In the days of the Kate Smith Hour Yogi Berra would still have been a baseball catcher for the NY Yankees and not yet managing the NY Mets. Arguably in baseball his comment applies more accurately. No fat lady closes a baseball game. Like all New Yorkers of that time, Yogi Berra would have known that Kate Smith was the fat lady who ended the broadcast night, however.
Kate Smith, who weighed 235 pounds, performed "God Bless America" on occasion before Philadelphia Flyers hockey games. Her performances were said to bring good luck to the Flyers and led to the indelicate saying "It ain't BEGUN 'til the fat lady sings!" See Kate Smith.
During his trademark broadcasting style of Australian Football, Australian Radio announcer Rex Hunt often 'sings' in the style of the fat lady, "IT'S OVER!" when he believes a team is in front by a margin which cannot be recovered by the opposition. In the rare cases of a team recovering that margin, he sings "REVO STI!" ("It's Over" backwards)
Former Indian cricket player and now commentator - Navjot Singh Sidhu has also used many a times this expression during his stint as commentator and made it very popular in the cricketing world.