Despite being the shows primary protagonist, Jack Bauer is seen to be extremely ruthless and will stop at nothing in getting the answers he needs. This includes physically torturing suspects and also mentally torturing them by threatening their families, including children.
There is so much violence that the season 1 finale and some other episodes later on have an excessive violence warning.
Given that there is almost 200 hours of footage, it would be near impossible to describe every scene of violence that occurs in the show. That being said, scenes of shooting, stabbing, explosions, and/or torture are a given in almost every episode.
The main character Jack Bauer has a recorded 233 kills across the seasons with 4/5 kills as a result of gunshots and nine kills from season two onwards as a result of neck breaking. The shooting scenes usually do not show blood explicitly and usually has the person just fall to the ground.
For a brief overview suspect are interrogated usually are injected with a type of chemical that induces pain. Jack Bauer breaks a man fingers one by one, cuts man's finger off by one, shoots a man in the kneecap.
Some of the more "extreme" episodes feature viral outbreaks, plane crashes, toxic gases, hostage takings, and nuclear detonations.
We see several bloody bullet holes in various parts of peoples' bodies.
A man digs into another man's stomach with his bare hands to retrieve a computer chip.
A man slides a knife into another man's kneecap.
A man is graphically shot in the head with a sniper rifle.
A man's arm in amputated offscreen.
In season 8, we see many graphic images of men who have been tortured and killed by Jack Bauer, including some graphic torture scenes.