Wormtongue is not a family name, as far as I know.
Sackville-Bagginses are debatable, as you said. Of course, we would mean Lotho here. But from what we know about Hobbits, and even from what is said in the Scouring of the Shire, it seems that his intentions were not actually evil. So, furthermore, we are leaving all hobbits out of that.
So, I believe here it is stated at the point I wanted it to appear: we're looking for three surnames of some who had evil intentions in mind. We do not include any hobbit in that. I'm waiting for your answers
EDIT: Cross-posted with
TM. Frodo is another possibility, at the Sammath Naur point, but we might say, it was not his own will that was guiding him at that moment. He repented after that. I'm looking for some who didn't repent, I'm looking for some who really meant it (I think it was not Frodo's intention to rule Middle-Earth even at that moment), I'm looking for some, who would you really place into the rubric labeled "EVIL".