Kieran Culkin actually starred in Home Alone alongside his brother but no one clocked

The Succession star started his acting career in Home Alone

And when it comes to Chrimbo films, there can be no doubt that Home Alone is right up there in the elite tier.

Watching Kevin McCallister (Macauley Caulkin) protect his family home from the Wet Bandits is essential viewing every December.

But whilst you may feel like you know every line and scene like the back of your hand by now, here's something new you should watch out for next time you stick Home Alone on - Macauley Culkin's brother, Kieran.

Yes, Kieran Culkin - who plenty of you will know for his role as Roman Roy in Succession - actually appears alongside his younger brother in Home Alone, in what was his first on-screen role.

Now, you might assume he plays one of Kevin's siblings in the film, but you'd be wrong.

The actor actually stars as Kevin's younger cousin, Fuller a.k.a. the one who wets himself.

At the start of the film when the family are all eating pizzas in the kitchen, Fuller, in his glasses and dungarees, is told to "go easy on the Pepsi," likely because of his reputation as a bed wetter.

But this character detail ends up playing a big part in the film's narrative. In the film, Kevin is meant to share a bed with Fuller the night before the family all jet off on vacation.

When he understandably voices his unhappiness at potentially sleeping next to a bed wetter, his mum tells him to sleep in the attic then.

And the rest is movie history.

Kieran doesn't just appear in the first Home Alone alongside his sibling, with Fuller reappearing in the sequel Alone in New York.

The actor was only eight years old when he appeared in the festive flick, and he's previously revealed how he didn't understand the film's plot until he saw it in cinemas.

Speaking to James Corden in 2020, Culkin said: "There's a part in the movie where there's a kid who gets his head counted incorrectly and he goes, 'Bye, bring me back something French!' I thought the movie was about that kid.

"And it made sense when I saw it. I remember seeing it in the theatre at the premiere and I was dying laughing and I was like, 'Oh, that makes sense 'cause Mac was on set all the time.'"