Elvis has left the building
During the early 1950s, Colonel Tom Parker was exclusively managing the hugely successful country singer Eddy Arnold. But Parker had become bored and part of him longed to get back to grass roots. He knew two useful guys out of Chicago, Al Dvorin and Tom Diskin: Dvorin ran his own talent agency and had done some work with Diskin, who managed the Dickens Sisters (part of the Eddy Arnold show) and just happened to be his siblings.
In Diskin, Tom Parker recognised exactly the sort of man with whom he needed to work: short, wiry, well-spoken and polite -- indeed, he was almost the exact opposite of the Colonel and would be an ideal and complementary partner. They formed a small promotions and bookings company named Jamboree Attractions and Diskin acted as the frontman while Parker lurked in the shadows.
Often, they used Dvorin's agency to provide acts for their touring country & western shows, and all was building nicely until in May 1953 Eddy Arnold learned what Parker had been doing behind his back and ended the Colonel's 25 percent management contract.
But the team of Parker, Diskin and Dvorin carried on working together, and when Parker landed the Presley contract in late 1955 they all realised they'd hit the big time. Diskin acted as Parker's right hand man for the rest of his life, and Dvorin accompanied the Presley concerts almost everywhere they went, filling in backstage wherever and whenever necessary.
At one gig, the emcee hadn't shown up and Parker thrust the microphone into Al Dvorin's hand, explaining that from now on "Big Al" was going to make the announcements before and after the show. Dvorin had no experience of public speaking and fearfully improvised on the spot: as Elvis finished his concert and leapt into his waiting car to escape the screaming crowd, Al switched on the mike and intoned, "Elvis has left the building. Thank you and good night".
It was a line that he continued to use for the rest of Elvis' career and it subsequently became one of the most recognisable phrases in the English langauge.
[Picture copyright Al Dvorin's family, Hawaii November 1957: Al Dvorin, Colonel Tom Parker, Lee Gordon (promoter) and Tom Diskin.]