Most painful death?

[SirFrog]

Slowly rot away but with your nerves completely intact, feeling all the pain.

[Handertaker]

getting a nuclear bomb blown right inside you

i think that not going to be painful becose you have no time to feel it

[Silverthorn]

time for me to add something...

Being tied up on a rope upside down... sounds harmless but this was actually a method to kill people in the medievals...
Same when you get tied up around your stomach and are hung until you rot away (sacrificing for an old German god, called "Wotan")

[sadbhav]

getting a nuclear bomb blown right inside you

i think that not going to be painful becose you have no time to feel it

slowmotion nuclear bomb

[Handertaker]

it still kills you fast but i think thats feels painful.

[sadbhav]

Being PM'd by 1000000000000000000 people 1000000000000000000000 times for 10000000000000000000000000000 days?

[SirFrog]

Would you die of that?

Anyway:
Being electrocuted slowly.

[Handertaker]

you are wake up in operating room.
you feel everything what is done to you.
doctors cant see you are awake.
thing what they are doing to you takes 5h and you are alive the whole time.
at last when it ends you die to heart attack.

[Drahcir]

39 lashes with a Roman whip.

[STM1993]

There's nothing more painful than an emotional, mental, spiritual pain. Because when that happens (given it is extremely severe, but I don't think it has happened before), you'd feel weak and completely demoralized, you can't help but think of that emotional suffering. You'd become extremely vulnerable, your mind induces pain that doesn't even exist and makes you hallucinate and have nightmares. At the same time, you feel the fear to die, making you suffer this for an extremely long time.

This would only end if somehow, you're comforted and relaxed, which is almost impossible because if its so severe you'd have gone insane. It would also end, if you actually killed yourself in one way or another, out of desperation.