No free equivalent exists that would effectively identify the article's subject, who is a copyrighted Fox character.
The image does not in any way limit the ability of the copyright owners to market or sell their product.
The image has been published outside Wikipedia; published as an extra on a DVD intended for widespread distribution.
The image is rendered in low resolution.
The image meets general Wikipedia content requirements and is encyclopedic, identifying Homer and the creative stage behind him.
The image meets Wikipedia's media-specific policy.
The image is used in the articles wiki-linked in the section title.
The image shows Sideshow Bob in his first appearance on The Simpsons. Following this appearance, his design was noticeably altered; the image allows users to compare the designs and aids the text.
The image is used in the article namespace.
The image has a brief description that identifies the image, notes the source, and provides attribution to the copyright holder.
This image is an illustration of a character or characters in a comic book, video game, or animated television program or film. The copyright for it is most likely held by either the publisher/producer and/or artist(s) producing the work in question. It is believed that the use of low-resolution images of character artwork:
for commentary on the character or characters in question,
where no free equivalent is available or could be created that would adequately give the same information,