Which artist is XXX co-written and recorded by?
Waiting for the End
``Waiting for the End'' is the only single to be performed at all concerts in the A Thousand Suns World Tour (``The Catalyst'' was not performed at the Sunrise, Florida concert; ``Burning in the Skies'' never received a full performance until the Australia leg; and ``Iridescent'' was not performed at most concerts at the Australia leg).