[cnn-photo-caption image= http://i2.cdn.turner.com/cnn/2009/images/09/05/art.day.jpg caption="Felicia Day, creator/star of web series 'The Guild,' re-enacts a scene from the show's music video with a costumed fan."] You may recognize her from guest appearances on "House," "Monk" or "Buffy the Vampire Slayer," but Felicia Day may be best known for co-starring in the hit online musical short film "Dr. … Continue reading 'Dr. Horrible' star finds success online