What would you call someone who sells information? [closed]

Is there an actual term? Just wondering since in movies or books there are those whom have information that other characters want or need and thus pay 'em for such information.

You're probably thinking of an information broker:

a person or company providing information to clients for a fee -- definition from Dictionary.com

TVTropes.com also lists a knowledge broker:

This is the person who always seems to have the dirt on everybody. The person who runs an information-gathering system, with a network of informers.

In crime fiction: informant or CI (for confidential/criminal informant).