I have used monsters adapted from Bloodborne, Dark souls, Pokemon, Monster Hunter, Mass Effect and Dead Space.
I have also made dragons that fight a bit more in the style of Dragon Age inquisition's dragons such as setting up guards that have to be broken to knock their hp down, elemental mines that go off if a creature enters the radius or if they don't level the radius by the end of their turn depending on the dragon, a separate set of actions they can take when they are flying in the air on a turn called a fly-by barrage that they then have to land after completing., and being able to summon dragonlings to help fight among a few other things.