Among other artists who have performed in a non-competitive manner are Danish Europop group Aqua in , Russian pop duo t.A.T.u. in , and American entertainers Justin Timberlake and Madonna in and respectively. Other notable artists, including Cirque du Soleil (), Alexandrov Ensemble (), Vienna Boys' Choir ( and ) and Fire of Anatolia (), also performed on the Eurovision stage, and there have been guest appearances from well-known faces from outside the world of music, including actors, athletes, and serving astronauts and cosmonauts. Guest performances have been used as a channel in response to global events happening concurrently with the contest. The in Israel closed with all competing acts performing a rendition of Israel's winning song "Hallelujah" as a tribute to the victims of the ongoing war in the Balkans, and a dance performance entitled "The Grey People" in 2016's first semi-final was devoted to the European migrant crisis.