Monos

Monos was a Necrotist, part of an artistic movement which believed that death was the highest form of art. He visited London in 2012 and began turning people into Leximorphs, imprinting his name on the entire population. When he attempted to put this method into practice on a large scale, the Eleventh Doctor had Amy and Rory deliberately scramble the TARDIS Translation circuit, thus causing all language in the area to be scrambled and illegible. With Monos unable to imprint his name on anyone as nobody could understand it, the Doctor and DI Bill Stringer accidentally electrocuted him while trying to capture him. (COMIC: Sticks and Stones)