Spencer was explaining the provenance of Pepe, which has became a symbol for white nationalism, when a man wearing a mask or bandanna attacked him.
Spencer later responded to the attack on Twitter, condemning the violence.
“He came out of nowhere, sucker-punched me,” Spencer said. “It’s a bad scene.”
Spencer said he feared this would become “the meme to end all memes,” but that no one should worry. “I can take a punch,” he said.
The inauguration, he said, is too intense.
“I don’t know what exactly I’m going to do now that I’m a target,” he said. “I don’t know if I need a full-time bodyguard or what.”