Definitely not spider mites or aphids, neither of them are capable of making holes in leaves. I could sure go with the possibility of slugs, however.

Or caterpillars?

Anything that makes holes that large should be pretty easy to find. If you don't see anything on or around the plants, you will need to make a nighttime excursion with your torch and I'll bet you will find the culprit in action. My guess is slugs.

Earwigs?

It isnt slugs. I have a good anti slug routine.

I am guessing it is earwigs because I have found a few of them in my greenhouse.

Need to keep an eye out :)