Some cheeses are never vegetarian

Rennet is used to set cheese.

The curds are what get turned into cheese.

When a calf is slaughtered, the lining of its stomach is washed, dried, and softened.

cheese on table

From here, rennet can be extracted, ready for use in cheese (viaThe Vegetarian Society).

Why not give halloumi a try, for example?

man making cheese