Not sure if this is a bug or known, but I have a undead zombie and skeleton gnoll who are well "dead" but they will not leave the party. their dead bodies travel from area to area with me, like perished party PC's that you haven't drop or resurrected yet. Possible useful facts: 1. They were commanded by Lareth who then left the party leaving me his army of undead. 2. Originally there was about 8-10 undead the rest when they died went away these two seem permanently attached.