The Demonic rats are a horde of small rat-like monsters that were accidentally created by Raven in "Fear Itself".
Character history[]
When Raven looses control of her fear in "Fear Itself" and refuses to admit it, her powers disappear and her fears manifest in the forms of various demonic creatures. After Robin and Beast Boy are taken away by the monsters, Raven, Starfire, and Cyborg search the tower but cannot find them. To Starfire’s discomfort, they decide to search in the depths of the Towers basement. Unknown to them, Raven’s fears create the rats as they wander through the darkness. The creatures stalk the three from the shadows waiting for the right moment to strike. One of the creatures scurrying across the floor is seen by Starfire, causing her to fire a starbolt at it, but misses. Raven and Cyborg didn’t see it and thus they continue to move on, while Starfire sees another and attempts to shoot it again. Annoyed, Raven insists that there is nothing to be afraid of, pointing out that its probably just some common rats.

The demonic rats pulling a screaming and struggling Starfire into their swarm.
In horror, Starfire states the demons are not rats, when a horde of them comes out of the shadows and attacks the Titans. The three attempt to flee, with Raven and Cyborg running for the exit while Starfire floats and fires her starbolts at the demons in the hopes of slowing them down. However, some rats on a support beam jump down on Starfire as she is distracted firing her blasts. Her panicking causes her to lose her concentration, and she falls right into the horde, just as Cyborg and Raven make it to the stairs. The demonic rats quickly surround Starfire, with a huge mass of slowly climbing up her body all the way up to her waist. The terrified girl fires multiple starbolts point blank into the beasts but does no good. Pulled into the swarm, Starfire unleashed an enormous scream as she is submerged into the pile. Cyborg attempts to rescue her, both she and rats disappear without a trace.
The rats later reappear alongside the Wicked Scary Monster and attack Raven when is alone. Though at first she is terrified of the monsters, Raven finally admits her fears and with that is able to conquer them, causing the rats and all the other monsters to back away from her in fear. Raven then destroys them all for good.