Because Hawkfrost set a trap for Firestar so Brambleclaw could become the leader of thunderclan. but he didn't want his leader to die that way so he killed Hawkfrost to save Firestar.
He got his throat slit by his brother. Hawkfrost attacked Brambleclaw and he is pierced in the neck by the stick from the fox trap. Brambleclaw, his Half-brother, never meant to kill him.
Brambleclaw does kill someone. He killed Hawkfrost because hawkfrost tries to take over the forest.
*Spoiler Alert* No Hollyleaf does.
He kills him by using a part of the fox trap that was supposed to kill Firestar
Brambleclaw and, in some chapters, Leafpaw.
Some people don't like Brambleclaw because of his relationship to Tigerstar and because he was tempted to kill Firestar. However, Brambleclaw did prove his loyalty when he killed Hawkfrost to save Firestar.
Sorry there is no Hawkhead is the warriors series, there is Hawkfrost (Brambleclaw's half-brother and Mothwing's of Riverclan brother.)
Haawkfrost died when Brambleclaw stabbed him in the stomach with a stick. This was when Hawkfrost trapped Firestar in a fox trap and was about to kill him when Brambleclaw stuck with loyalty and turned on Hawkfrost.
He dies when Firestar gets stuck in a fox trap and he wants Brambleclaw to kill Firestar so he can be leader. Brambleclaw reacts to his leader instead. Next, Hawkfrost threatens to kill Brambleclaw. He thinks quickly and shakes up the pole from the fox trap. Letting this get tamperd, he grabs the sharp pole and right when Hawkfrost pounces, she nails it right into Hawkfrost's throat.
Goldenflower. He is the half-brother to Brambleclaw and Tawnypelt. Goldenflower had a unknown tom as her mate and gave birth to Swiftpaw. Then, Goldenflower had another mate, Tigerstar. She gave birth to Brambleclaw and Tawnypelt. Brambleclaw, Tawnypelt, and Swiftpaw shared same mother, but had different fathers.
No, but he tries to kill Hollyleaf, Jayfeather, and Lionblaze because he thought that if Squirrelflight watched her kits die then she would go to Ashfur. But Hollyleaf, Jayfeather, and Lionblaze are not Squirrelflight and Brambleclaw's kits.
He and Brambleclaw were with Firestar, who was stuck in a fox trap, and Hawkfrost told Brambleclaw to tighten the trap and kill Firestar, but Brambleclaw killed Hawkfrost instead, fulfilling the prophecy "Before there is peace, blood will spill blood, and the lake will run red."