FORTUNE — Everything went according to plan. The CTO’s presentation at the annual conference grabbed the audience’s attention with a memorable storyline, visuals worthy of an Apple new product launch, and unmistakable “marching orders.” She told them why they should care and what she wanted them to do.

But then came the question-and-answer period.

An underpaid and over-caffeinated software engineer in the seventh row wanted to know why the company had decided to discontinue a certain product. And then he wanted to hear about the company’s policy on worker rights at a supplier in Asia. And then he had another thing on his mind, and then another.

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None of this had anything to do with the CTO’s presentation. But in an effort to be helpful, she tried to answer his questions, dragging herself into a contentious and lengthy back-and-forth that quickly made the audience completely forget all the important information she had delivered before.

Hecklers come in many forms, among them:

• The Narcissist – luxuriates in the sound of his own voice.
• The Falsifier – asks a question or makes a statement containing incorrect information.
• The Phantom – claims to possess information but won’t reveal the source.
• The Omniscient Authority – demands that you know the answer to any conceivable question.
• The Machine-Gunner – asks several questions in rapid succession.

Unfortunately, business etiquette prohibits you from unleashing your inner Louis C.K. and telling the heckler to “Shut the @#$!* up!” But you don’t want to get dragged down the rat hole. It’s about your priorities, and you want to keep the content (in both your presentation and the Q&A) focused on your goals.

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So if you’re confronted with an audience member who wants to argue or pontificate:

• Touch and go. Deal with the offending question swiftly and then return to your topic.
• Take it outside. If the same miscreant keeps trying to dominate the conversation, say you need to move on to stay on schedule and offer to discuss the questions one-on-one after you’ve finished speaking.
• Give others a chance.  Say, “I’d like to hear from other members of the audience” and call on them.
• The eyes have it. Don’t encourage the filibusterer by continuing to make eye contact. Look at others in the audience.

You did a lot of work to develop and deliver your message. Don’t throw it all away by letting questioners with their own agendas seize control.