Ghouls may be kind of gross and/or ugly, but they're not especially dangerous. They're kind of look like ogres, but the worse they'll do is just growl or throw stuff around.
Muggles don't much like them, but wizards sometimes end up letting them stay around as family pets.
(Harry Potter book shout out: In Harry Potter and the Deathly Hallows, Ron and his family transfigure their family ghoul to look more like Ron suffering from a very bad case of Spattergroit so the real Ron can go hunt for horcruxes with Harry and Hermione.)
This insect makes a sweet and sad syrup that counteracts that hysteria that comes over you when you eat Alihotsy. That's handy.
It's pretty bad if Glumbumbles infest an actual beehive, but otherwise they just nest in dark and secluded places and keep to themselves.
Gnomes are common garden pests. The only way to get rid of them is by picking them up, swinging them in circles until they're dizzy, and then flinging them over the garden wall. Adios, gnomes!