The retail experts have weighed in and the "it" costume for this year is in: 

Superhero.

That's the biggest seller so far for 2016.  Here are the top 5 so far for children, adults, and pets.

Children:

1.  Action/Superhero

2.  Princess

3.  Animal (cats, dogs, lions, etc.)

4.  Batman

5.  Star Wars

Adults:

1.  Batman Characters

2.  Witch

3.  Animal (cats, dogs, bunnies, etc.)

4.  Marvel Superheros

5.  Vampire

Pets:

1.  Pumpkin

2.  Hot Dog

3.  Bumble Bee

4.  Star Wars Characters

5.  Devil