LOS ANGELES • A fan wrote to the Star Trek actor: "@WilliamShatner I thought you might want to know you're dead."
He also posted a screenshot of an advertisement that carried a tribute to the actor.
An upset Shatner then shot back at Facebook, which had promoted the advertisement, tweeting: "What's up with you allowing this Acocet Retail Sales ad to pass your muster?"
According to People magazine, Facebook's director of product management Rob Leathern later informed the actor - who celebrated his 87th birthday yesterday - that the advertisement had been yanked out.
The screw-up is the latest blow for the social media giant after reports surfaced that political data firm Cambridge Analytica, which worked for Mr Donald Trump's presidential campaign, had managed to mine the accounts of more than 50 million users.
Last month, online reports also surfaced on Facebook - and Twitter - that said Rocky star Sylvester Stallone had been knocked out for good, prompting the actor to deny the news that he had died.