Famous for: The Guild, Dr. Horrible's Sing-Along Blog
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Day writes, directs and star in The Guild, an internet sitcom about MMO addiction that blew up when it premiered in 2007. She also starred in Joss Whedon's hit musical Dr. Horrible's Sing-Along Blog. Basically, she does it all—acting, singing, producing—and did we mention The Guild is based on the years she spent addicted to WoW? What a trooper.