Elon Musk has admitted he has Asperger syndrome, as he hosted the US TV comedy show Saturday Night Live.
He revealed he has the condition, which is a form of autism, as he explained he has difficulty getting people to know whether he means what he says.
The 49-year-old Tesla CEO, SpaceX founder and one of the world's richest men, said in his introductory monologue: "It's great to be hosting Saturday Night Live, and I really mean it. Sometimes after I say something, I have to say that I mean it."
He added, in explanation, that he is the first person with Asperger's to host the show: "Or at least the first person to admit it."
It is thought to be the first time the businessman has publicly said he has a condition on the autism spectrum.
The UK's National Autism Society says that diagnoses of Asperger's are being used less frequently compared to previously but while "many people who fit the profile for Asperger syndrome are now being diagnosed with autistic spectrum disorder instead... some people with a diagnosis of Asperger syndrome may choose to keeping using the term".
The society says that people with Asperger's can find it harder "in particular, understanding and relating to other people, and taking part in everyday family, school, work and social life".
Mr Musk also joked about his Twitter account, which has more than 50 million followers, and the tweets that led some people to complain he had been invited to front the show.
He said: "Look, I know I sometimes say or post strange things, but that's just how my brain works."
"To anyone who's been offended, I just want to say I reinvented electric cars, and I'm sending people to Mars in a rocket ship. Did you think I was also going to be a chill, normal dude?"
Mr Musk is one of the top three richest people in the world, although his position in that group has fluctuated in the last 12 months.
Forbes Magazine currently puts his fortune at $177bn (£126bn), making him the richest person to host the show, which is frequently fronted by Hollywood royalty or other public figures.
During the show, his mother, model Maye Musk, came on stage to talk about what he was like when he was 12.
NBC took the opportunity to live-stream the episode globally on YouTube, the first time it has ever been viewable simultaneously around the world.
Mr Musk had a go at acting when he played a doctor who delivered bad news to a group of youths, using a form of slang.
Jokes about cryptocurrency throughout the show, including those made by Mr Musk, appeared to hit the value Dogecoin - the virtual currency he had previously touted - the value of which fell during the show, ending up down by about 12% from late Friday.
The billionaire is thought not to be the first with Asperger's to host the show, with comedian and Saturday Night Live alumni Dan Aykroyd who hosted in 2003 having spoken in the past about being diagnosed with a mild form of the condition.