Just Scourge
Firestar killed him after he took one of Firestars's lifes.
The answer is unknown. He killed many cats. He wasn't evil, just misunderstood. Scourge The Cat killed different cats to see the best way to get his revenge on Tigerpaw/claw/star. Here is the list of all the cats that I know he killed: Firestar(x1), Tigerstar(x9), A rouge, ...?
Yes, he did, but only for defensive purposes. He killed Scourge, the evil leader of BloodClan. I don't think he killed any other cat.
Tigerstar(ThC) was the former deputy of ThunderClan and the leader of ShadowClan, receiving the name “star”. He is well known for being evil. He attempted to kill his own leader and the deputy after him, Firestar. He continuously battled Firestar, even after death, resulting his spirit to be killed by Firestar.
Firestar
if you mean the blood clan leader in the warriors series, firestar killed him,i believe
He lost it when ShadowClan and ThunderClan were battling, Russetfur killed Firestar and Lionblaze defended his leader and killed Russetfur.
Firestar, Graystripe
Firestar
usally firestar and his allies
No, she killed Ashfur and she's dead now, so I don't think she will kill Firestar.
Yes, he did. Erin hunter revealed in an online chat on wandsandworlds.com that both Firestar and Scourge had the same father, thus making them half-brothers. Firestar killed Scourge in the last book of the first series.