These creatures are all mythical and legendary beasts found in various cultures from around the world. I think the bull snake and chicken snake work particularly well, as they look strange and a bit disturbing. The chicken snake (cockatrice) and basilisk are also interesting because reptiles and birds are linked (dinosaurs and evolution),so a very literal hybrid of the two works quite well. This theme of reptiles and birds is one I am keen to develop further.
Some of these creatures are also heraldic beasts, meaning they were often shown in medieval manuscripts and banners. I think this is an interesting concept as images of these mythical creatures could be found in many places (churches, architecture, banners, books, stained glass windows and signs) and there were probably a lot of people who believed these beasts existed.