It's back to the future for Martin Henderson next week when he makes his debut on Kiwi screens on hit medical drama Grey's Anatomy.

The expat movie and television star is excited about New Zealanders seeing him play Dr Nathan Riggs, aka McKiwi, his global moniker in reference to him replacing former Grey's Anatomy heartthrob McDreamy (Patrick Dempsey), years after he made his first medical soap appearance in Shortland Street.

"It's wonderful to be a part of a big international cast for a show that's not only just popular in New Zealand but in the far-flung corners of this beautiful planet," he told Spy.

The show's creator, Shonda Rhimes, obviously likes Kiwis as she has cast Step Dave's Jono Kenyon as the male lead in her new show Toast. Rhimes approached Henderson for Grey's Anatomy after previously casting him in her short-lived South American medical drama Off the Map.


"It was a series of conversations. I was working on a show that was cancelled, so I was available.

"I had worked with Shonda a couple of times before and she said she wanted to talk to me about some 'stuff.'

"She wasn't very specific, then she started talking about Grey's Anatomy, which was exciting."

Henderson thinks his first acting role on Shortland Street was harder work than Grey's Anatomy.

"Anyone working on that show [Shortland Street] at that pace is doing a great job just to remember all their lines. This show is definitely more forgiving. We do one episode every 10 days. There's a lot of set-up so if you don't totally know your lines in the wide shot you kind of know them by the time you do your close-ups - don't tell Shonda I said that!

"It's funny. Every now and then I'm standing at reception, I've got my clip board, I'm going through my lines and I'm waiting for action. It's the same environment as Browns Bay all those years ago."

Season 12 is well under way in the US and Henderson has a new fan base because of the famous show. But he isn't kissing and telling about whether he takes up where McDreamy left off.

Offscreen, Henderson has been hanging out with another Grey's Anatomy newbie and fellow singleton in Hollywood, Giacomo Gianniotti, who plays Dr Andrew DeLuca.

The pair were both dateless on Valentine's Day, so ended up at Henderson's house, then a neighbour invited them over.

Henderson was asked to make pavlova, but - sacrilege - he did not know how. Apparently guests were pleasantly surprised by the pav Gianniotti whipped up.