LMW-tan is the moe anthropomorphic mascot of the Lost Media Wiki; also known as "gijinka", this is when any concept (including a website) is represented as a cute anime/manga-like girl!
Previous website-based examples include Wikipe-tan and Trope-tan, so here is LMW-tan.
She was inspired by the protagonist of Cracks, a lost animated short which was possibly the most famous lost piece of media on the Wiki. She is thus also wearing some green, which is the color theme of the website.
Originally, she was just some fanart done for fun, but gained enough appreciation to become the official mascot!
LMW-tan is a shy but curious and passionate little lady, who has a passion for old movies, TV shows, cartoons and even video games. If she learns of such a thing that is lost and impossible to view by the common people, you can bet she will do the best efforts to obtain it, for the greater good!