Disclaimer- I don't own warriors. Doesn't Erin Hunter?
Tigerstar.
You were trained viciously with Thistleclaw. He taught you to kill, a skill no true warriors use. Hopefully, that training would just make you a good warrior. But it didn't. So now, you are forced to wander through the Dark Forest, or the Place Of No Stars, forever.
How many murders, attempts to murder, and sins did you do? You probably killed many cats. How many stars in the night sky were killed by you? Too many. Lets list your crimes.
You murdered Redtail to become deputy. Your ambition fired your claws at Redtail's throat. You killed him, and lied about it.
You set up a trap for Bluestar to die on the Thunderpath. But poor Cinderpaw, she was caught in the trap instead, resulting in her crippled leg. You changed her life, from the bouncy, energetic, blue-eyed apprentice, to the wise and respected medicine cat at she was before she died.
You brought a group of rogue whom used to be with Brokenstar into the forest. You planned to murder Bluestar and blame it on the rogues. But Fireheart, now Firestar, stopped you.
As a rogue, you savagely slaughtered Runningwind. He died. Because of you.
A pack of dogs got loose in the forest. You caught prey for them, and then laid a trail of dead rabbits between the dogs' lair and the ThunderClan camp to lead them to us. You murdered Brindleface, and left her near the camp to give the dogs a taste for cat blood. Firestar was the only reason ThunderClan wasn't ripped to shreds.
This is why you are in the Dark Forest, Tigerstar. Your crimes speak for themselves. But you still wanted revenge, didn't you? In the Dark Forest, you recruited Clan cats to get the revenge you wanted. But you failed, as Firestar killed you, just after the thunder killed him.
Tigerstar, you have a killer's mind.