[Salone]

Followers do not die...sort of. When they lose all health, they crouch for a while to rest up before rejoining the fight.

However...

Do NOT, I repeat, do NOT ever ever hit a follower if they are low on health or resting. Your damage can kill them. So be mindful with those flamethrower hands of death. Also, watch where you shout. I have knocked her off a few cliffs with Unrelenting Force.

There's one Follower who is not as fragile though. If you want it spoiled, highlight the empty spot below.

Lucien Lechance is an obtainable follower.

The one follower is actually a summon who stays permanently. Once he takes fatal damage (You murdering him, or certain other conditions), they can be summoned again without penalty. The Summon power only works once a day, but they will last forever until murdered.