Hello Art and Sterf!
I think most of us can agree that mythology and fantastical beasts and creatures are great. They can give inspiration, help you work through that artist’s or writer’s block, make your worldbuilding better, or even just help alleviate your boredom. But they’re not always easy to find, and sometimes it’s all too to go for the default ones even if they’re not quite what you’re looking for.
Maybe a lesser known creature would be better? Maybe you’re looking for a different cultural connection? Either way, it can be difficult to find them, and sometimes we don’t even know what we’re looking for. This is where Wikipedia comes in handy. It’s for free, and if you find the right pages, you can find almost anything.
Now, of course it’s better to do your own research than to blindly trust in Wikipedia, but when you don’t even know where to start, it can be great to have a name or place to point you in the right direction:
Legendary creatures by name: More like a dictionary than anything else. But if you have a hunch of what something is called and you want to double check that you’ve got the right thing, or if you just want to browse, it’s very useful.
Legendary creatures by type: Very thorough, and has creatures from many different cultures. It lists creatures according to animal similarity, various themes (body parts, attributes), and even habitats!
List of fictional species: For when you want to check what’s been done before, how, and where.
List of theological angels / demons: Angels and demons are common archetypes, but often there are lesser known names and variants that might spark an idea. (Especially demons. There are a lot of demons.)
List of mythologies, creation myths, world epics: Sometimes it’s better to start with context! There are so many different cultures across the world that sometimes they slip our mind, and sometimes we’ve simply not come across them before. Now, I don’t want to encourage taking an entire culture’s myth of origin and passing it off as your own. But exposing yourself to different ways of thinking about the world can help you ask the right questions to better flesh out your own worldbuilding.