We make them often so have done them with loads of different combinations but these days do tend to have our favourites
Ours are always as thin as possible, and then have a thin layer of homemade tomato sauce.
And there's always mozzarella, the balls, not the solid sort you grate. Not having been to Italy I rely on Tv and books but we do try to make them as authentic as we can, ie not too loaded and not too much cheese.
Torn slices of prosciutto or Serrano ham, scrunched a bit, thin-sliced red onion, a sliced mushroom or 2, halved black olives.
Red onion, chorizo, black olives, sliced red chilli, red pepper.
Prawns, big ones halved through the middle, red pepper, anchovy, capers.
Prawns, red onion, red pepper, red chilli, black olives. Plus a few spinach leaves if I have them.
Leftover roast meat (any kind, but pork, lamb and chicken work well also turkey), either cut small or processed and mixed with garlic, chilli, cumin, coriander, a touch of oil, lemon juice. Or mixed with Cajun seasoning (nice with chicken). Plus red onion, black olives.
Sliced artichoke heart, prosciutto/serrano, red onion, black olives.
Red onion, red and green peppers, sliced cherry tomatoes, black olives.
Red onion, thinly-sliced salami, red pepper, red chilli (and black olives!)
Red or white onion, pre-griddled sliced peppers and courgette, basil leaves.
White or red onion, sliced mushrooms marinated with olive oil, garlic & oregano, black olives.
There are probably more, but these are fairy regular ones. Things like the artichoke hearts will appear 2 or 3 weeks in a row because that's how long the jar lasts
They're lovely with prawns too.
Also, sometimes I put the veg on raw but often will cook them a bit in the oven while it's heating up, they do tend to be a bit wet otherwise if you have many of them.