Well, there's still Adaware
"Free" AV. It's becoming a thing of the past. First Avast, which used to be an excellent product, sold out and became nearly as bad with their constant pop-ups as the adware that they're supposed to block, now AVG abusing your privacy that they're supposed to help protect. I'd rather a company just discontinue their free offerings if they're going to do this. It's insulting and makes the world just a little worse place to be in, while actually free AV did the public a service and earned a lot of goodwill IMHO, though I understand that goodwill doesn't keep the lights on.
At least Linux is still truly free... at least until MS releases their distro.