Is there any essential followers you can get? I'm tired of followers dying in battle and I want someone who can't die. If possible could you list a mage. Also what do I have to do before I can get the person as a follower etc (If needed). Thanks

I don't use followers, however from what I hear, they are semi-Essential, that is they can die, but only if the player is the one to land the killing blow. NPCs can't kill them. I'm not sure if this applies to all followers however.

I've noticed that Lydia and Breylna only die if you kill them. So, just be aware of were they are in a battle.

All companions die if you kill them, or they get hit to much when they are down (enemies usually leave them alone when they are down). Also its where*.

But that means doing all of the quests haha, i've done the questline but on another character

Another reason I was asking about essential followers is because I want to have 2 followers, one as a mage, one as a thief

Also will mage followers wear the robes you give them if they are better? i.e giving them master robes if they are already wearing novice robes?

ETA: can't have more than 1 follower

I read somewhere you can, as they are quest related and dont replace your current follower

you can have 1 human and 1 dog at a time, if that's what you mean

oh i see, you mean temporary guys - sure that happens, but you can't control those like real followers

Barbas is invincible and cannot be killed.

I meant I read somewhere that you can have multiple (human) followers as some of them you gain from starting quests

You could level conjuration, and use dead thralls. You can have 2 thralls (with the right perk) and a companion active at one time. Level conjuration quick by casting soul trap on a dead enemy repeatable, if you want to. You could get two mage thralls and a mage companion?

but when they die, they turn to ash dont they? rather than going on their knee then getting back up when they have some health again

When they die, they don't turn to ash, they just fall to the ground, and you have to use the dead thrall spell again.

They can die from other means.

When they drop to their knees enemy aggro targets you so they can recover but splash damage or an AoE from the enemy can still kill them.
Also if you are hidden or outside enemy ability to detect you and your follower is on his/her knees in the middle of them... you'll see Lydia die pretty damned quick.

Basically they are hard for enemies to kill as long as you are in the fight, but they are not immortal, without you to draw aggro they are actually pretty squishy.