A vengeful ex-boss has the potential to make your professional life miserable, or even derail your career. A former employer may hold a grudge over real or perceived slights or injustices, be jealous of your success or be resentful you left your previous position. Protect yourself from this unprofessional behavior by taking immediate action to stop the vengefulness and clear your name.

Unwarranted Vindictiveness

An ex-boss who’s being vindictive over a petty matter, such as your getting a promotion or plum job he wanted, is displaying childish unprofessionalism. This type of person might talk poorly to former colleagues, say negative things about you through industry organizations or trade groups, or attempt to blackball you with clients and vendors by spreading false and misleading information. If you have proof of this type of behavior, take it to your ex-supervisor’s immediate boss for mediation. The bad behavior is a reflection on the company, and your manager’s boss should be interested in curbing the unprofessional actions.

Anger Over Past Relationship

An ex-boss might come across as vindictive, feeling he’s justified because of some previous negative interaction between the two of you. For example, if you left your job and convinced key clients to come with you to a competitor, your boss is likely to feel anger and resentment at what he considers disloyalty. While this doesn't justify vindictive behavior, it requires careful steps on your part. If he tells others of your perceived disloyalty, you may be questioned about it by future prospects and employers. Characterize the situation as being a strategic, above-board, business-only move and resist the urge to bash your boss in return.

Talk to the Ex-Boss

Although it might be an uncomfortable conversation, consider confronting your ex-boss about his vindictive behavior. Having a face-to-face discussion might be enough to dissuade your boss from carrying on, particularly if you outline the steps you'll take to stop the behavior, such as going to his supervisor. A personal meeting also gives you the opportunity to clear up misperceptions that might be contributing to the behavior.

Legal Implications

If an ex-boss attempts to slander you, spread false information, or otherwise misrepresent your professionalism, you may have legal options to stop the harassing behavior. Collect evidence of what your ex-boss is saying or doing, such as posts on social media accounts, emails or other negative correspondence he’s shared with other colleagues. If other professionals in your industry have firsthand knowledge of your ex-boss bad-mouthing you, ask for the details to be documented in writing. Consult an employment law specialist for advice on how to proceed.