Three-eyed carp, six legged deer, five winged dove. Only joking. So, when people left, they often left their livestock behind, sometimes pets, too. So there are feral cattle, feral horses, feral dogs, foxes, deer, elk, wild hares, boars, I think even European bison. Interestingly, mammals seem to be less affected by the radiation than expected. Not so much the case for birds and amphibians in the area, which seem to be almost entirely absent. Insects show some interesting genetics, for example, beetles with otherwise predictable spot patterns on their carapaces, have unusual patterns in the area. Some otherwise unknown species of microbes have been found in the direct vicinity of the reactor, some who have developed the ability to use radiation as a food source. I would say that, if you are planning a trip to the area, first I would recommend against it due to the political turmoil between Ukraine and Belarus, second I would recommend against it due to the high prevalence of thyroid cancer in the area, likely due to the accident. Thirdly, I would very strongly recommend against hunting or foraging in or near the exclusion zone, as there are a lot of poisonous chemicals present, probably due to the accident.