While designing a website, an important element is designing a 404 error page. 404 error pages are those, which visitors get when they try to reach a web page or file on your site that is missing or non-existent. These pages should be designed creatively, complimenting your site and should contain all the useful information to help visitors. Here we are featuring 20 most creative and helpful 404 error pages. We hope it would be a source of inspiration for you while customizing your own 404 error pages.