Cook pasta according to package directions until al dente. Drain, rinse under cold water, and set aside.
In a large bowl, combine cooked pasta, olives, cherry tomatoes, mozzarella balls, cheddar cubes, bell peppers, and onion.
Toss with Italian dressing until evenly coated.
Season with salt and pepper, then sprinkle with parsley or basil.
For spooky touches: place sliced olives on mozzarella balls to make 'eyeballs,' and scatter throughout the salad.
Chill for at least 30 minutes before serving.