Okay, I am looking for pictures of a fictional character for example. Wikipedia offers free images and some with free image licences, except for fictional characters, you get this message. For example I need a picture of freddy krueger for my blog, could I use the image or not. It states this- "This is a copyrighted image that has been released by a company or organization to promote their work or product in the media, such as advertising material or a promotional photo in a press kit. The copyright for it is most likely owned by the company who created the promotional item or the artist who produced the item in question; you must provide evidence of such ownership. Lack of such evidence is grounds for deletion. It is believed that the use of some images of promotional material to illustrate: the person(s), product, event, or subject in question where the image is unrepeatable, i.e. a free image could not be created to replace it on the English-language Wikipedia, hosted on servers in the United States by the non-profit Wikimedia Foundation, qualifies as fair use under United States copyright law. Any other usage of this image, on Wikipedia or elsewhere, might be copyright infringement. See Wikipedia:Non-free content and Wikipediaublicity photos. Additionally, the copyright holder may have granted permission for use in works such as Wikipedia. However, if they have, this permission likely does not fall under a free license. Please note that our policy usually considers fair use images of living people that merely show what they look like to be replaceable by free-licensed images and unsuitable for the project. If this is not the case for this image, a rationale should be provided proving that the image provides information beyond simple identification or showing that this image is difficult to replace by a free-licensed equivalent. Commercial third-party reusers of this image should consider whether their use is in violation of the subject's publicity rights. To the uploader: This tag should only be used for images of a person, product, or event that is known to have come from a press kit or similar source, for the purpose of reuse by the media. Please add a detailed fair use rationale as described on Wikipedia:Non-free use rationale guideline, as well as the source of the image and copyright information. Additionally, if the copyright holder has granted permission, please provide further details as to the terms."
The key here is likely commercial third-party use, and that is going to depend on exactly how the image is used and whether or not your blog is commercial i.e. takes in any revenue. Revenue can be defined as advertising revenue (adsense), the sale of merchandise, donations for bandwidth, memberships, etc. If you are worried about any possibility of being sued for infringement (which is probably very low) then you should try and get permission from the copyright holder.