T-elos's challenge

 is a track in Xenosaga Episode III. It has not been released on any soundtrack or sound selection and not much is known about this track.

It plays when T-elos confronts the party in Rennes-le-Château.

A version of the track without the main melody section, unofficially referred to as , plays when the party finds the Vessels of Anima in the core of Labyrinthos.

Another version of the track with only the main melody section, unofficially referred to as , plays when Shion confronts her father about using her mother as a test subject.