Such as?
Discussion
if somebody's a serial rapist and they aren't trying to rape you, you should still feel justified in killing them
Could still be considered defense, simply defense of others.
right, but "defence" is a really wide description, far wider than self defence. Defence of your property, defence of your culture, defence of your way of life, etc, etc. (note that lots these are difference from self defence, as self defence typically refers to self defence in a physical manner.)
I once stabbed a man for cheating at capture the flag.