These examples might fit your requirements...
1) The Jersey Devil. Outrageously rare, never photographed, approximately the weight of a light human (S.W.A.Guesstimate of 80-150 lbs, my mother is in that weight range). A lot of people believe it is a myth.
2) Melanistic (black) cougars. Seldom photographed (never a good one), no bodies, a couple of hair samples, same weight range as a regular cougar - 115 to 198 lbs. Biologists will tell you that cougars don't come in black and the photos are of out-of-scale domestic cats.
My personal sasquatch is the American pine marten. I first learned about them in my hunter safety course in Wyoming. I've never seen one (same for bigfoot), never met anyone who has seen one (I have met people who have claimed to see a bigfoot), never seen one in a zoo, never seen the corpse or pelt of one, and I have seen more photos of sasquatch than photos of American pine martens. I would like to see a pine marten more than I would like to see a sasquatch, as pine martens can't tear my arms out of their sockets.
There is no evidence that sasquatch are real, until you see one for yourself. That is why I look.