Rory Culkin and girlfriend Kate Arizmendi are first-time parents

Rory Culkin and his girlfriend Kate Arizmendi have welcomed their first child.

The Signs actor and the Succession cinematographer are the parents of a baby girl named Havoc Moon.

Announcing her arrival via her Instagram Stories on Sunday, Arizmendi posted a photo of the newborn sleeping, with her tiny hands tucked under her chin, and revealed that Havoc was born on Saturday.

She added, "We're so in love (with) you," with crying emojis.

The director of photography followed it up with a picture of Havoc looking wide-eyed at the camera shortly after her arrival.

"15 mins after pushing her out and so alert and excited about life already," she wrote. "Also hello girl baby Rory."

Arizmendi then posted two snaps of Rory, 36, having skin-to-skin contact with Havoc and described him as the "best papa".

The 38-year-old went back and updated her January pregnancy announcement post, revealing that their daughter's full name is Havoc Moon Alva Culkin.

She added, "We love her. She rules us already."

The Scream 4 actor, who is the younger brother of Macaulay and Kieran Culkin, began dating Arizmendi in 2023.

He was previously married to camera assistant Sarah Scrivener between 2018 and 2022.

Havoc Moon will have several cousins - Home Alone star Macaulay has two children with his longtime partner Brenda Song, and Succession actor Kieran has three kids with his wife Jazz Charton.