The Bestiary, introduced in the Winter Update 2017, features several creature classes which differ a little bit from this wiki's creature classes. After fully unlocking all entries of one class you will get an according character title, which is semipermanent, that is, you will only lose it if a future update adds new creatures under the said unlocked class. To regain the title, it will only be necessary to fully unlock the new creatures, not the older ones. Also, the title Executioner is granted if all Bestiary classes are completed. It is lost and regained the same way for individual classes' titles, but with a lot more of effort involved, a true challenge for completionists.