“Doctor Who” is already a legendary, decades-spanning sci-fi series that has gone from a 1960s British favorite to a global embrace.

Today’s new season launch achieves several remarkable firsts for the 15th time-traveling extraterrestrial known as Doctor Who.

He’s the immensely charming, record-busting Ncuti (pronounced Shoo-tee) Gatwa who is not just the first gay, Black Doctor — he’s also the first actor in the role who wasn’t born in the UK.

Gatwa was born in Rwanda in 1992. Two years later the family fled the genocide against the Tutsi to settle in Scotland.  In 2013 he graduated from the Royal Conservatoire of Scotland.

He won attention — and a BAFTA award — for “Bad Education” and was featured in “Barbie.” But Doctor Who is something else.

“When my agent called me to let me know that I had the part, my mouth just dropped and I was silent for about five minutes,” Gatwa, 31, explained in a Zoom interview. “Because I just couldn’t get my head around the concept. ‘Doctor Who’ was such an institution, a cultural institution in the UK! To think that I was going to be at the helm of that felt very, like, beyond humility.

“Beyond, this isn’t me being humble. I just couldn’t cerebrally wrap my head around that concept. So there was a slight bit of hesitation — just because I knew that it would come with a lot of pressure and expectation. Then, eventually, it was a no brainer. I knew creatively it was going to be such a fun job.”

Asked why the Doctor has achieved this unheard of longevity, “I couldn’t tell you,” he answered. “If I knew I would bottle it!  Because there is something interesting, something magical about the show. Something about it that just gets to your heart and you love it.”

The 13th Doctor, Jodie Whittaker, was the first female Doctor Who. With his casting what, if anything, does this mean in the Who universe? Is it really a big step?

“I guess it is. It’s a show that’s about time-traveling aliens. For me it has always, since its inception, lent itself to the notion of diversity. Of anyone being able to play this character because, narratively, they are shape shifting.

“And that’s another really special thing about the show — that many people from many walks of life are able to watch the show and feel like, ‘I’ve got a place.’ They see themselves as the companion or the Doctor. Whoever they feel like, there’s a place in the show for them, which is another thing I think is magical about the show.”

“Doctor Who” streams May 10 on Disney+