Serial killer is a popular theme for fancy dress parties, even though it is a little bit politically incorrect. There are lots of options for serial killer fancy dress.
Dexter Fancy Dress
Dexter is the fictional american tv series serial killer. He’s a good man who struggles with his inner demons and channels his killing urges in to only killing the bad guys.
Each episode features a kill chamber section where Dexter dresses up in medical/butcher gear, which will leave no trace of the murder on him, and then kills his prey.
To dress as Dexter there are two looks you can go for. For kill room Dexter you need to go for a big plastic butchers apron (the kind somebody in a slaughter house would wear), surgical mask, slaughter house boots, butchers knife and a mean expression.
Hannibal Lecter Fancy Dress
For Dr Hannibal Lecter fancy dress the most iconic look is the straight jacket with face mask along with an orange prison jump suit. You could also bring along a wine glass with some red wine, or only drink red wine at the party. If anyone asks you what you are drinking simply same a nice chianti without any further explanation.
American Serial Killer Fancy Dress
One of the most famous US serial killers was Ed Gein, who was the inspiration for some of the Psycho and Silence of the Lambs movies. He was famous for keeping the bodies of victims, or digging them up from a local graveyards, and fashioning keepsakes from their bodies.
This could give you some ideas for some gruesome keepsakes for your outfit. Perhaps get a tan lamp shade, stitch it in several places and apply a bit of fake blood to make it look like a human skin lamp shade.