The Dark Past, known in Japan as Messenger From the Darkness (闇からの使者 Yami kara no Shisha), is the fourth episode of Ultraman: The Ultimate Hero.
A pair of seismologists working in a remote cavern have detected unusual underground activity. Theresa Beck and Kenichi Kai are sent to investigate and Kai disappears when another tremor rocks the cavern. While Beck tries to console herself for losing Kai, the rest of the WINR team has determined that the seismic activity is being caused by a strange object moving underground toward the city. That night, a a gigantic armor-plated lizard emerges from the underground and begins a destructive rampage in the city. Meanwhile, Kai is being held prisoner by a race of underground people who have lived underground since the destruction of the dinosaurs. It is these underdwellers who have sent the lizard-like monster, whom they call Telesdon, to destroy the human world so that they can once again rule on surface. Telesdon fled underground to avoid being blinded by the sun's light. Soon, a game of "cat and mouse" is set up to lure Telesdon to the surface to be blinded by natural lights, but the trick doesn't work as Telesdon was not weak against other forms of light. After a scuffle with the underground people, Kenichi Kai turned into Ultraman Powered and went to the surface to fight Telesdon. As Powered and Telesdon were fighting, WINR attempted to blind the creature with magnesium flares. After the flares were fired in Telesdon's face, Powered used the Mega Specium Ray to destroy him.
- Captain Russel Edlund: Harrison Page
- Theresa Beck: Sandra Guibord
- Julie Young: Robyn Bliley
- Rick Sanders: Rob Roy Fitzgerald
- Kenichi Kai: Kane Kosugi
- At 22:38, a wire is seen blowing up as one of the explosion igniters are activated on Telesdon.