Raccogryph: A hybrid creature with the head and wings of a crow, and the body of a raccoon. About raccoon sized, and flocking. Smarter than either of the base creatures, but thankfully lazy. Popular as burglar pets and as familiars.
Rakfallia: An underground dwelling terrestrial cephalopod, resembling an octopus, but with more tentacles. Weighing several hundred pounds, and extremely strong, a rakfallia hunts by hauling a collection of half-ton rocks up to the ceiling of a cavern, camouflaging itself, and waiting for prey to pass below. Their primary weaknesses are that they cannot throw, and their top land speed is on par with a brisk walk. Their thick hide is tough and rubbery, giving them good resistance to clubbing and cutting attacks. If threatened, the beast can emit a spray of fine powder apparently comprised of equal parts capsicum and glutamate: penalties to vision and bonuses to deliciousness. Rakfallias are highly intelligent, and the young ones can be tamed.
Random Number Generator: Like glitches, the name dates back to the Divine Era. A squirrel sized, bug-shaped mass of elemental Thunder energy. They can bite for electrical damage and knockdown. Any time they teleport, you are guaranteed to have one to four more of them upon arrival. Fortunately, once a swarm achieves critical mass, it attracts wild elementals that will feed upon them. Of course, then you have to deal with the elementals…
Rat, Haunt: Start with a large rat, give it the ability to casually sound like an attic ghost just by breathing. Haunt rats can also produce terrifying howls when establishing territory, and once a day a scream that will stun creatures as large as a troll.
Rat, Large: Your tier one, basic fantasy rat. About the size of a house cat. Solo, a threat to small children. In groups, a serious threat to unarmored adults.
Raven, Divine Servant: It is said that all corvidae serve the Raven Queen, but these, eagle-sized ones do so as a sentient worshiper base. They all appear to have their queen's signature ability to copy, steal, and share memories.
Revanant: The undead incarnation of Wrath. Whatever killed them so angered them they got right back up again, and will pursue their killer with a relentless, unstoppable rage. Thankfully, beyond the ability to destroy any barrier between them and their target, they appear to have no more supernatural abilities than your average Stone Troll.
R.O.U.S.: “Rodents of unusual size? I don't think they exist” - Dread Pirate Roberts. A rat the size of a Pumakin. Aggressive and vicious, they fortunately do not normally attack in groups.