Dysfunctional Leadership
In the case where an executive is still in place and continuing to wreak havoc on the organization, typically, a board, or sometimes a mid-level manager, will contact a consultant for the purpose of getting advice and help with making the decision of what should be done. In this case, only a board can act, but it's not uncommon to see a mid-level manager go over the executive's head directly to the board and uncover serious issues that are going on that are being perpetrated by the executive. In this case a consulting project becomes very delicate, and you have to consult with key members of the organization often without knowledge, or at least the participation of the executive in these consultations.
If the executive is made aware that the board is approaching a consultant, the executive usually becomes very defensive, and it can aggravate the effects of their authority in place in the organization. You have to be very careful about how you set this up, and make a commitment to act very quickly. Regardless of what your decision is, there nothing worse than having an abusive executive in place for a long period of time. The longer they’re there, the more damage they do and the more bridges they burn, and more needs to be cleaned up after they're gone.