It could be a groundhog. They often eat just part of the fruit. Or it could be a tomato horn worm. Looks for small black specks (droppings) and check the plant to see if some of the foliage has been eaten too. If so, look for the worm and destroy it.

Tomato hornworms can be enormous--easily 6 inches long. I'd say you have a huge one. Or two. This year I found 9 one day and 1 the next--on fewer than 10 plants. They were all huge. That's the most I've ever found. Some years there are none.

If the tomatoes are being eaten that much by hornworms your plant leaves would most likely be badly eaten, too. Since you don't mention anything wrong with the leaves my vote goes to one of the other critters...but I don't know which one.

Mine look like that after a night's Snail Feast, so I'm thinking snails /or slugs.

I really appreciate all of the helpful responses. I found some hornworms (wow, they are well camouflaged!), so I am chalking up the damage to them for now. Hopefully I'll be able to enjoy the rest of the tomato fruit without other critters beating me to it. Thanks everyone!