A few times after a long and/or harrowing re-entry, I've EVAed Kerbals that appear to have taken permanent damage (permanent in the context of the mission they are on) while they were inside the ship. There is a bar, like the thermal warning bar, only this one isn't going away when the heat goes away. This is thermal damage, correct? I've seen the same thing when I once EVAed a kerbonaut in the upper atmoshpere only to quickly get him back in when the heat bar appeared and rose alarmingly quickly. That one might have disappeared after he got back in the ship; I don't know.
Can kerbonauts die of this damage even if the ship is okay?
I have a picture, but I don't want to create an imgur album for this sole purpose, unless you guys insist on seeing evidence.