Question: when did the guy who played robbie rotten die
Answer: Stefán Karl Stefánsson ( / ˈstɛfən ˈstɛfənsən / ; Icelandic : ( ˈstɛːfaun ˈkhartl̥ ˈstɛːfaunsɔn ) ; 10 July 1975 -- 21 August 2018 ) was an Icelandic actor and singer , best known for playing antagonist Robbie Rotten on the children 's television series LazyTown .