The pair famously met on the set of the show - where their characters Jon Snow and Ygritte had an on-screen romance.

A publicist for Harington said the couple were "delighted" to welcome a daughter but gave no details on the name.

The actors married in 2018 at Leslie's ancestral castle and already have a two-year-old-son.

Speaking before they tied the knot, Harington said: "If you're already attracted to someone, and then they play your love interest in the show, it becomes very easy to fall in love."

The 36-year-old revealed their second child was on the way during an appearance on US show Jimmy Kimmel earlier this year.

He said his son "was about to get the shock of his life" to have a sibling - and said he was also "terrified".

"You know with the first baby you're like walking on clouds and dancing through fields of daisies for nine months," said the star.

"But this time the reality check comes much shorter, you get practical real quick."

Harington was also tight-lipped on whether a rumoured Jon Snow spin-off was in the works. His brooding character was a favourite among Game Of Thrones fans.

"I can't say anything on that," he told Kimmel.

The actor joked: "I've got a tally in my head of how few photos I get asked for in a day, and when it get below a certain number I think I'll do the spin-off."