In general, yes, they must, and if they use your copyright work without your agreement they commit an unlawful act.

There are a few exceptions:-

• If you have previously assigned copyright to someone else you have surrendered all ownership and negotiating rights. The copyright holder must grant permission.
•  Certain types of usage are regarded as 'fair use' and are allowed by copyright law. It is still polite for the user to ask, but they are entitled to use the work so long as it really does fulfil the criteria. Infringers frequently excuse themselves on the grounds of fair use meaning not-for-profit, or that any image found on the web is eligible, or similar misunderstanding of the law.
• If you have previously released the image under licence, usage within the terms of the licence does not require permission. Uses outside the scope of the licence are still protected by copyright law and require your agreement. For this reason do not grant licences that allow wider usage than necessary.