"Viva Las Vegas" is a 1963 song written by Doc Pomus and Mort Shuman and recorded that same year by Elvis Presley for his Viva Las Vegas film vehicle, which along with the song was set for general release the year after. Although Presley never sang the song live, it has since become widely known and often performed by others. The RIAA, on their part, credits the song as having sold 500,000 copies in the United States alone, as per their Gold Award certification, issued on March 27, 1992.

Released as the b-side of the "What'd I Say" single from the same film, "Viva Las Vegas" charted separately from its A-side, a modest hit reaching #29 on the Billboard Hot 100 pop singles chart. The Elvis version of "What'd I Say" peaked at #21, the two sides having equivalent appeal in the marketplace. "Viva Las Vegas" reached #12 on the UK Singles Chart, improving to #15 after a reissue in 2007.

In the years since its first release, the song has become one of Presley's most recognized numbers. In the 1990s and 2000s, the song appeared in countless movies and TV sitcoms, either as a reference to the city of Las Vegas, or simply as an expression of joy or bewilderment in related comedic situations.

In 2002, the city of Las Vegas requested Elvis Presley Enterprises, the company that handles a portion of Elvis's legacy and all Elvis-related music rights, to allow it to be the official song of the city. Negotiations stalled over the price requested by EPE, notwithstanding that EPE had not controlled the copyright to the song since 1993, at which time it became the property of the families of the songwriters Doc Pomus and Mort Shuman. Since EPE no longer owns the copyright to the song, it essentially means that EPE does not have the authority or right to negotiate the use of the song "Viva Las Vegas" within the United States, its territories and possessions, although EPE may be able to negotiate the use of the actual Elvis recording of the song.

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