Yes, yes there are Zombies on earth.
Although the type of "eat your brains" Zombies aren't really a thing and probably will never be - unless we have a nuclear war or something along those lines - there are parasites that control the minds of their hosts, essentially turning them into bugs.
Don't worry, as far as I know this only happens in the insect world where things are way worse than they were for us in the medieval ages. According to some sources I've read these parasites basically control the host to feed off of their brains (hah) or to use their bodies for something.
Here's a link to read a bit further on the subject: https://news.nationalgeographic.com/news/2014/10/141031-zombies-parasites-animals-science-halloween/