And Musk seemed to specifically reference the 92-year-old Holocaust survivor’s background by comparing Soros to Magneto — a Jewish supervillain who “fights to help mutants replace humans as the world’s dominant species,” as Marvel’s official character description puts it.

“Soros reminds me of Magneto,” Musk posted at 10 p.m. Monday, apropos of nothing. The tweet triggered a flood of replies comparing Soros to various symbols of evil, recalling long-standing conspiracy theories that paint him as a godlike billionaire Jew who uses his philanthropic foundations to flood Europe with refugees and corrupt American politics.

The left-wing commentator Brian Krassenstein replied to Musk, pointing out that Magneto is a Holocaust survivor in Marvel lore, where the character manipulates magnetic fields to oppose (and occasionally help) the heroes of X-Men films and comics. “[Soros], also a Holocaust survivor, get’s attacked nonstop for his good intentions which some Americans think are bad merely because they disagree with this political affiliations,” he wrote.

Musk replied to Krassenstein five minutes later: “You assume they are good intentions. They are not. He wants to erode the very fabric of civilization. Soros hates humanity.”

His tweets were condemned Tuesday morning by Jonathan Greenblatt, chief executive of the Anti-Defamation League, which has catalogued similar conspiracy theories that hold Soros wants to control the world.

“Soros often is held up by the far-right, using antisemitic tropes, as the source of the world’s problems,” Greenblatt wrote on Twitter. “To see Elon Musk, regardless of his intent, feed this segment — comparing him to a Jewish supervillain, claiming Soros ‘hates humanity’ — is not just distressing, it’s dangerous: it will embolden extremists who already contrive anti-Jewish conspiracies and have tried to attack Soros and Jewish communities as a result.”

Musk, who has gutted Twitter’s media relations department, could not immediately be reached for a response.

Soros, who was forced into hiding as a Jewish teenager in Nazi-occupied Hungary, is the focus of international hostility for his wealth, religious background, investments and Open Society Foundations, which spends hundreds of millions of dollars promoting democratic institutions and liberal causes.

Glenn Beck attacked Soros in a three-part Fox News series titled “The Puppet Master” in 2010. Donald Trump has accused him of meddling in U.S. politics. Conspiracy theorist Alex Jones has spread lies that Soros turned on other Jews during World War II and collaborated with Nazis.

Musk, who has used his position to amplify extreme-right personalities since he bought Twitter for $44 billion last year, sounded much more ambivalent about Soros a few months ago, when his company was still investing in Tesla.

Asked in January by Ian Miles Cheong — a far-right commentator who has since called for Soros to be arrested — what questions Musk would ask the philanthropist, Musk replied: “Do you actually know where your money is going?”

In March, Musk jumped into a conversation with the far-right Twitter user Catturd, who was promoting a mostly false claim that Soros donated $1 million to New York’s district attorney.

“Soros figured out a clever arbitrage opportunity,” Musk told Catturd. Small political contests, he said, “have much higher impact per dollar spent than the big races, so it is far easier to sway the outcome.”

In fact, The Washington Post’s Fact Checker found the claim highly misleading and wrote that it “plays into stereotypes of rich Jewish financiers secretly controlling events.”