The rake, eh? In my opinion, a very ugly alien or just a horror story. Since it’s supposed to reside in the forest, and the forest hides many things. Like, caves in forests sometimes hide reptilians, some forests hide greys, even bigfoot is hiding in there. And dark spirits come out at night in the forest where many paths of the forest cross. Fortunately there are forests who don’t have dark things hiding in them. I wouldn’t be surprised if the rake had a connection to an alien hybrid, though the rake is just a being that kills, it can’t think like an alien would.
Either the rake is a rumor or an alien that went wrong. Slenderman? I believe it doesn’t really exist, or it’s just a being that has been overloaded with terrifying rumors, but the chance of slenderman being an alien is high. Telepathy, high levels of energy that cause a human to pass out, ability to shape-shift and change it’s height, stalking people and then mind controlling them, teleportation. Yeah, it could be an alien or something evil. I don’t think being thin and tall has much to do with a being’s abilities though. Each being is different.
There are supposedly real journals of Slenderman’s encounters with people on the internet, more precisely, teenagers. Now, most of these encounters were a bunch of teenage gibberish. But some made very much sense with how the gates of spirits in the forest work, which could be just children’s imagination. Anyway, that’s another story. I believe most of these rumors about Slenderman and the rake are either not real, or myths loaded with horror.
As for the rest tall and thin beings, I believe each is different. You can never be sure.