But they're also the ultimate experts at roasting each other.
And they've done it again. Yesterday Devon Murray, who played Seamus Finnigan in the movies, tweeted that he'd just found a pair of Emma Watson's socks in an old bag.
People reacted like this:
Including Chris Rankin, who played Percy Weasley.
And Sean Biggerstaff, who played Oliver Wood, said what we were all thinking.
But, most of all, people made a LOT of the same joke.