Andrew Lincoln in The Walking Dead (2010)
RICK GRIMES went berserk on Joe's throat, while him and his group were being molested
*berserkers were ancient Norse warriors, known for the ability to get into uncontrollable rage before battle, which allowed them to fight with great strength and bloodlust, while also giving them immunity to fear and pain (thus giving rise to a modern term 'to go berserk')
Related poll: Big screen berserkers
Thanks to yrnej for some suggestions