Rats are the most common villians in the Redwall book series, as well as the TV series based on it. There are several main villains who are rats in the series, the most notable being Cluny the Scourge.
Rats are rodents closely related to mice, but bigger. There are several different types; including bildge rats, sea rats, sewer rats, tavern rats, water rats, dockside rats, and woodland rats.
They were, without notable exeption, vermin (barbarians). They were often quite feral, even cannibalistic, and tended to be hordes beasts. They were the most common race of vermin, and often the lowest ranking. This is due to the fact that they tended to be weak and/or stupid, with several being defeated by one warrior. There were exceptions, however; with rats serving as officers, and sometimes even horde leaders.
There were many rats in the horde of Badrang the Tyrant, an infamous Northland stoat. Most of them were probably sea rats due to the fact that Badrang and his vermin were pirates before settling on the North Eastern Coast and founding Marshank. There, they built a mighty fortress by use of slaves they captured on their many exploits. The fortress was never fully constructed, and was meant to be the foundation of Badrang's empire.
There were also many sea rats in the crew of Troman Cuttlefish Clog, another great stoat pirate, and a former friend of Badrang. But he came to Marshank to take a great deal of its slaves. When Badrang refused to give Clogg anything, the two hordes became enemies. But Badrang eventually beat Clogg and captured his crew. When given the choice between death, slavery, and recruitment, they joined the ranks of Badrangs army.
After Martin the Warrior and his alliance conquered the fortress of Marshank, many (perhaps most) of Badrang's vermin were slain, and the rest driven off.
A wildcat named Verdaurga Greeneyes led an army called the Thousand Eyes Army from the North to conquer Mossflower Wood. Once there, they recruited the local rats, weasels, ferrets, and stoats. As usuall, the majority of the army were rats, but none of them officers. The Army was headquartered at Katir, Verdaurga's fortress, and lived off of the food that Verdaurga taxed the woodlanders in return for protection and residency.
In his old age, Verdaurga became very ill, and left the ruling of Katir to his evil daughter Tsarmina. This resulted in a decrease in discipline among the troops. Also, the winter was very hard, and resulted in a food shortage. Many of the woodlanders left, and some formed a rebellion known as Korim.
As the war became more and more real, Tsarmina's sanity began to decrease. And those in the Thousand Eyes Army became doubtful, fearful and mutinous. They were joined by a mercenary band led by a fox named Bane. His mercenaries consisted of foxes, weasels, ferrets, stoats, and, of course, rats. But after Tsarmina discovered that Bane sought her kingdom, she tricked the eagle Argulor into attacking him, and the two killed eachother.
There are only two notable rats in the book. One is a soldier named Whegg, whose fate is unknown, and the Gloomer. The Gloomer was a feral black water rat, kept in the lake underneath Katir. Mindless and blooddrunk from years of being kept in the dark and treated like an animal, he was a dangerous and monstrous tool of the Thousand Eyes Army. He had poor eyesight, but an incredible sense of smell. This, combined with his monstrous stregnth and bloodlust, made him spot-on for his one and only purpose, search and destroy. But he was killed by a pike named Stormfin.
The war ended when Martin the Warrior and Korim flooded the valley of Katir, turning it into a lake and crumbling the fortress. Tsarmina attempted to escape, but was killed by Martin. Those of her troops who survived crawled ashore, weary and helpless. Korim was mercifull, and banished these survivors from Mossflower.
Rats played a much larger role in Redwall (which took place long after the freeing of Mossflower Wood). In fact, the main antagonist, Cluny the Scourge, was a rat.
Cluny the Scourge was a giant bilge rat of unknown origin. He was a legendary warlord, and had only one eye. He lost his left eye in battle with a pike, whom he killed. His standard was adorned with the skull of a ferret. His armour included a cloak made of bat wings, and his helmet was adorned with stag beetle horns. But by far his most notable feature was his tail, which was incredibly long and powerful. He used as whip (which earned him his title, "the Scourge") and fastened a poisoned barb to the end.
Cluny came to Mossflower with a large horde of sewer rats, tavern rats, water rats, and dockside rats. When he first arrived, he had at least four hundred rats. But he had two of his captain, Scumnose and Frogblood, take a pressgang of fifty soldiers and round up the woodland rats, weasels, ferrets, and stoats. He made his headquarters at St. Ninian's Church. Scumnose and Frogblood ended up with over a hundred new recruits, "mostly rats, but with a good scattering of ferrets and weasels, and the odd stoat.". This put Cluny at over five hundred (or even six hundred) soldiers (It is worth noting that some of them were forced to join through beatings at threats of death.). These new recruits gave Cluny the lie of the land, and told him about the wealthy and prosperous abbey known as Redwall.
Cluny took his army to Redwall, and demanded that they surrender unconditionally or die. When they refused, Cluny vowed to take the abbey by force and slay them all. He was determined to make the abbey his castle.
When inside Redwall Abbey, Cluny had a tapestry in Cavern Hole. On it was a warrior mouse that Cluny had seen in a nightmare. When he asked about it, a young mouse named Matthias told him that it was a picture of Martin the Warrior, founder of Redwall. When Cluny realized that Martin was a symbol from which the mice would draw courage, he formed a plan. He had his burgaler, Shadow (who was either a rat, a weasel, or even a bit of both) sneak into Redwall and steal it. He succeeded, but due to being caught in the act by Matthias, he was pursued to the ramparts, and accidentally fell to his death. But Cluny got the tapestry, and escaped.
Cluny later fixed Martin's picture to his standard as a banner, to mock the Redwallers. He led his army in an attack against the abbey, using ladder and grappling teams to climb the wall while archers and slingers fired at the battlements. But the Redwall defenders managed to fell every ladder and rope before any of the rats even reached the top. Cluny then decided to concentrate his fire on the west side of the Abbey, while he and an invasion party climbs a tall elm on the east side and uses a plank to get across and onto the wall while the defender were busy defending the west side. But as he was crossing, Constance the Badger appeared on the other side and kicked the plank off the wall. Cluny was barley alive after he hit the ground, and his army was forced to carry him back to the church in an undignified retreat.
Cluny managed to recover, and he waged many more battles in his war against the Abbey. In fact his army grew so strong that they eventually conquered the Abbey. But little did Cluny count on his nightmares being real. Matthias returned from his quest, with Martin's blade, and duelled Cluny, almost beating him. But Cluny bested Matthias and forced him into a bargain. However, Martin sliced off the Bell rope in two and dropped the Bell on Cluny's head, killing him. The rest of the Rats were slain in battle and those who escaped were killed by Captain Snow the owl and Squire Julian the wildcat, descendant of Verdauga.
The Rats return as one of the main forces serving Malkariss, Slagar's master and the Bigger Bad of the novel. Malkariss has Black Rats serving him, robed in purple. Malkariss sees himself as a deity and forces his Black Robes to worship him and keep order in his kingdom. However, when he captures the youngsters of Redwall Abbey by means of Slagar, this sparks a rebellion in the kingdom through Matthias trying to save his son Mattimeo. And then the slaves see the weak and treacherous Malkariss and stone him to death. His kingdom gone, the slaves are liberated, and Slagar's horde perish in the battle. Slagar himself falls into a well of the old Loamhedge Abbey and falls to his death.
Gabool the Wild seized control of the Rats and took them as his Army. He terrorized the oceans with his force and made many enemies. He stole Joseph the Bellmaker and his daughter Mariel, both Redwall mice, and threatened to kill them if Joseph did not say what his captive Bell read. Joseph deciphered as much as he honestly could then Gabool ruthlessly pushed him off the tower to his alleged death. In fact, Joseph survived and returned with Mariel to confront his enemy. All the rats in Gabool's fortress were slain and those that lived were made to promise to leave Redwall alone.
Southsward, a peaceful Southern kingdom, was under threat by an enemy they themselves had let into their castle. The plight of the Rats and two foxes was just a front, and they quickly usurped the kingdom. Joseph sent a dream message to Martin the Warrior and he enlisted help with Dandin and Mariel. Southsward was swarming with Rats. However, in a gigantic battle, all the enemy was deposed or dead and their leader, Urgan, was killed.
Damug Warfang, the main antagonist, is a giant Rat, and upon hearing of Redwall's weak South Eastern wall, he decides to conquer. However, he is met with fierce opposition from the Redwallers, and he is eventually defeated. His Rats were gigantic, and numbered a few thousand. They narrowly besieged the Abbey and conquered.
Rats serve as Ublaz's primary ground forces, but he relies on foxes more. Ublaz meets his downfall from the Rats. These are disloyal to him unlike his Monitor lizards and foxes.
The Rats are again the main opposing force - but these are water rats. Said to be disgusting to look at because of their pale colour, the water rats are the main force of Mokkan's army and they serve as his main loyal forces. They attack the Abbey several times - once in the night which is a successful attack given the Rats kill an Abbey owl and steal the famous Tapestry of Martin the Warrior, and also to exchange Dwopple, an Abbey babe who had been stolen, but ends in war, and also several times until the coming invasion. The Rats successfully take over after allying with some ferrets. The Rats finally perish in Redwall when the dwellers fight back, but those that survive are redeemed and told to move on and leave the Abbey be. In fact, this is the first time in the series the Rats are shown not to be wholly evil - the water rats are, in fact, pawns of the Marlfoxes, and the ones on their island are very peaceful, and some Rats actually start crying upon hearing Song's song about home. It is said the Rats eventually live in peace and get their island back, because the Marlfoxes stole the island from them in the first place.