Hello! Hi! Yes! Maybe I can help here!
Here are some very basic things to help people understand this:
The spirit in question, for those who can’t recognize it from the op (which is fair), is the w-ndigo (plural w-ndigoag). It is specifically from the Algonquin people, but it’s also been spread to other Anishinaabe tribes and cultures.
(Quick side note: Algonquin is a specific tribe while Anishinaabe is the cultural group. Think of it like a country in a continent, like how Japan is an individual country but shares some cultural aspects with some other East Asian countries because of cultural exchange and shared histories.)
We (Anishinaabe people) aren’t actually supposed to say its name, like the op said, especially in winter or at night. We believe that its name has powers and can call attention to it. Many people online censor it, while people irl will use other terms for it to avoid saying the name.
Usually, we only talk about it in detail at specific times. It’s not something to be casually discussed or used as a fun character in movies and games.
(We’re also taught not to whistle outside during winter nights because that calls its attention. It’s a running joke in a lot of Anishinaabe circles.)
The most likely theory behind its appropriation is that people who were invited to Anishinaabe story circles and other cultural events, with the expectation that they would behave respectfully, took our sacred stories and shared them without permission, butchering them in the process.
Everything about it in media is wrong! So, so wrong! In every way! The only accurate thing about in media is that it’s a cannibal spirit, that’s it.
It’s not a deer. It has never been a deer in Algonquin or Anishinaabe folklore and the idea is wild to me. Where did that even come from? Its actual physical description varies but it’s always humanoid and that’s as much detail as I want to get into here.
It’s very much a local spirit, based around the winters Anishinaabe tribes experience in the Northern US and throughout Canada. Trying to put it anywhere else… doesn’t make sense. This is aimed at you, Hazbin Hotel fandom. A w-ndigo would die from heat exhaustion in New Orleans.
The w-ndigo itself isn’t just about cannibalism, it’s about greed and selfishness and how taking everything you want makes you stop valuing the people and world around you and stop caring about who you’re hurting. A person doesn’t have to be a cannibal to become a w-ndigo, they just need to be a selfish asshole (and, depending on who you ask, Anishinaabe).
Many moden Anishinaabe people see the w-ndigo as just a warning and a metaphor; Potawatomi author Robin Wall Kimmerer used it as a manifestation of climate change and environmental destruction in her book Braiding Sweetgrass. Other Anishinaabe people, particularly those of us who are more spiritual/religious (like me!), believe the w-ndigo and other spirits to be real beings who deserve respect and care, not just scary stories.
And finally, this spirit is sacred to us. No, sacred doesn’t always mean good. The w-ndigo is a vital part of our cultures and our histories and it deserves respect. Our peoples have been massacred, our children kidnapped, our dances and languages and religions criminalized, our lands stolen, our spiritual leaders murdered. Please just leave our spirits alone. Let us keep hold of what little colonization and genocide has left us.