Musk, the inscrutable South African-born billionaire behind Tesla and SpaceX, visited Colbert's second "Late Show" episode on CBS Wednesday, after 6.6 million viewers turned up for Tuesday's premiere.
"I thought Scarlett Johansson was glamorous," Colbert said after greeting Musk onstage. (Johansson had been Colbert's first guest Wednesday.) "You're wearing a tuxedo jacket just as casual wear."
Referring to Musk's various business ventures, Colbert wondered, "Are you sincerely trying to save the world?"
"I'm trying to do good things, yeah," Musk replied matter-of-factly.
But he's a billionaire too, Colbert said. Didn't that make him, as the host put it, either "a superhero or a supervillain"?
"I'm trying to do useful things," Musk repeated.
Things got a little testy when Colbert referred to Musk as "one of the CEOs" of SpaceX, a space transport company. Musk said he was the one and only CEO.
"I'm sorry," Colbert said, as the studio audience laughed nervously. "Struck a raw nerve."
Musk went on to correct Colbert after the host said that a SpaceX rocket would land on a "barge." It was in fact a ship, Musk said; ships have engines and barges don't.
"Everything I say seems to be insulting you this evening," Colbert observed, a comment that drew little reaction from Musk. (No hard feelings, apparently: During a commercial break after their talk, Colbert reportedly told the audience that Musk should run for president.)
Maybe Musk's mind is on Mars. The billionaire said Mars is a "fixer-upper of a planet" that could be made Earth-like by warming it up. Unfortunately, in his view that would entail either exploding thermonuclear bombs on its poles -- which Colbert said sounded very supervillain-y -- or polluting the Martian atmosphere with greenhouse gases.
But the hard-to-faze Musk did reveal a sense of humor at one point. Colbert showed video of a Tesla contraption that automatically recharged an electric car with a robotic arm that bobbed and weaved like a cobra before finally landing on its target.
"For the prototype at least," Musk said drily, "I would recommend not dropping anything when you're near it."
Did you catch Colbert's second show? What did you think?