I’m going to a costume party tomorrow with a Hogwarts theme and having already been sorted into Hufflepuff house, I’ve been nominated to represent Cedric Diggory. It’s been couple years since I’ve reread the books, though, so I can’t remember any particularly distinguishing features of Cedric. (Excepting, naturally, his rugged good looks, which I’ve already got covered. :D) Any suggestions for something particularly identifiable as Diggory?
An Asian hottie hanging on your arm?
You speak in jest, but upon noting who’s in Ravenclaw, I just might be able to pull that off. 
He’s a top Quidditch Player, so maybe if you had a Golden Snitch in your pocket. Or you could choose to dress as a Quidditch Player, rather than just a school uniform.
You could also have a tiny dragon statuette, which he was given before the dragon challenge in the tri-wizard tournament.
Dead and grasping a cup?
I came in here to mention ‘being dead’.
You need a broom…Nimbus 2000 or better preferred…
I vote you go as Zombie Cedric. Get an old robe and tatter it, carry a busted broom and do some undead makeup. You can joke that you came back from the grave to attend the party.
It would be pretty easy on short notice!
If you’re doing the movie version Cedric, don’t forget the eyebrows.