Beyonce had been the name lighting up social media ahead of Vice President Kamala Harris's primetime address.
Celebrity gossip site TMZ had fueled the fire with an all-caps headline on its homepage screaming "performing at DNC's final night!!!" above a picture of the megastar.
Taylor Swift was also one of the names that circulated in media and political circles, with celebrity watchers trying to ascertain the whereabouts of private jets the pop icon has previously used.
Former Republican presidential nominee Mitt Romney, currently a US senator who has criticized former president Donald Trump, was even moved to deny it would be him.
"Contrary to fake news posts, I am not the surprise guest at the DNC tonight. My guess is that it will be Beyonce or Taylor Swift," Romney posted on X. "So disappointing, I know!"
His fellow Republican George W. Bush was put forward as a contender for the rumored surprise spot, with "Republicans against Trump" posting a picture of Bush embracing then first lady Michelle Obama to the account's 765,000 followers on X.
One wag suggested it would be the divisive Raygun, whose breakdancing efforts at the Paris Olympics spawned a plethora of mocking memes.
