Many people say that these cats are truly evil and should go/are in the Dark Forest. Some of these cats are simply villains to the current main character, but some of them are actually evil. Here are a few examples of these cats. Also, beware of Spoilers for ALL the books.
Thistleclaw = Thistleclaw's most famous act is when he goaded Tigerpaw (later Tigerstar) to attack and almost kill Tiny. Thistleclaw didn't actually kill any cats, or break the Warrior Code in any way. Although Thistleclaw did train in the Dark Forest (his mentor was Silverhawk), he never actually harmed any of his Clanmates. Many people say that he made Tigerstar evil, and that since he told Tigerstar to attack Scourge, that the BloodClan battle was his fault. Bluestar actually hated Thistleclaw since he was a kit, because Thistleclaw was arrogant. Thistleclaw actually had no reason to join the Dark Forest, as he never broke the Warrior Code. Also, Bluestar chased Thistleclaw out of StarClan, and Thistleclaw then joined the Dark Forest. He actually loved Snowfur, who was Bluestar's sister, and he might of loved his son, Whitestorm, too. Bluestar didn't trust him because of his ambition to become leader (actually, Bluestar also wanted to become Clan leader), but how could she be so sure the Thistleclaw would of destoyed ThunderClan? What if becoming depudy, and later leader, had made him change? Blackstar did. Why shouldn't Thistleclaw? Thistleclaw didn't deserve to go to the Dark Forest, and since Bluestar chased him there, it's sort of her fault.
Tigerstar = Tigerstar's father, Pinestar, 'left' him when he was a kit to go and become a kittypet. This explains Tigerstar's hatred of kittypets. Also, he was born with natural courage and strength, but Thistleclaw taught him to use it badly, but it wasn't Thistleclaw's fault of how Tigerstar used his it. Tigerstar also killed Redtail, his deputy, when he saw the chance. Tigerstar might of had ambition, like Thistleclaw, but unlike Thistleclaw, he killed for it. Since Firestar came to the Clan, Tigerstar (during the Last Hope) said that when Firestar came to the forest, Bluestar simply pushed him to the side. Tigerstar could of used his strength for good, and following the Warrior Code, Tigerstar might of become a warrior whose legacy would be told to many other cats for generations. Tigerstar also attacked Scourge, but he was told to do so by Thistleclaw. Remember this: Pinestar left him, so Tigerstar has no father figure. Since Thistleclaw was his mentor, Thistleclaw became his father figure. Tigerstar did break the Warrior Code, many many times. He was so angry with ThunderClan and the other Clans, that even in his death, he sought out to kill Firestar and weaken ThunderClan. Tigerstar even went as far to come back to the Clans in spirit-form and try to kill Firestar and ThunderClan. Tigerstar does deserve to go to the Dark Forest, but remember that he lost his father, sisters, and he later on lost his mentor, at a young age.
Ashfur = In my mind, Ashfur over-reacted. So, Squirrelflight left him. Squirrelflight became Bramblestar's mate and had kits (I know they weren't hers, but Ashfur didn't know that). So Ashfur tries to kill Firestar, and then later on tries to kill Lionblaze, Jayfeather, and Hollyleaf. Many Ashfur-fans say that Ashfur was justified, because Squirrelflight had left him for Bramblestar, or that Squirrelflight was using Ashfur to make Bramblestar jealous. Both are false. Squirrelflight broke with him cleanly and told him the truth, which is correct to do. Also, Squirrelflight was never using Ashfur to make Bramblestar jealous. Take a look at this in a human-kind of way. You have a girlfriend that you love. She dumps you, and later on marries another guy. She and that guy have children. That kind of happens all the time. You don't go insane, try to kill her father and children, and do whatever else Ashfur did. According to Yellowfang, he only 'loved' too much. Well, so did Mapleshade. And she's in the Dark Forest. Ashfur should of gone to the Dark Forest, because he and Mapleshade had pretty much the same issue.
Blossomfall = I know that she isn't really a villain, but this isn't actually about completely evil cats. Her mother completely ignores her and pays much more attention to Briarlight. In a human way, this actually does happen. When a mother had a hurt child, she usually pays more attention to the child than her other children. Millie isn't exactly abusive, either (yes, she yelled at Blossomfall, but some parents do do that). Blossomfall should understand that Millie is overprotective of Briarlight because of her injuries, and anyway, why be jealous of a crippled littermate? Does Blossomfall want to be like Briarrlight, dragging herself around? I don't hate Briarrlight, or Millie, or any of these cats for that matter. I just am pointing out that Blossomfall should try to understand her mother and littermate's conditions better.
I know I didn't add many cats, but I wanted to get these four things out there : Sometimes cats shouldn't be treated like villains, because sometimes it is unjustified. Some cats are truly evil, but sometimes had a bad past. Some cats over-react or are plainly evil. Some cats are simply jealous and really aren't villains.
What do you think about these cats?