The Sentinel is a complete Sonic the Hedgehog story which appeared in Issue 29 of Sonic the Comic. This story is notable for sowing the seeds of the Drakon Empire, but they personally would not come into fruition until after the Final Victory.
Earthquakes are nothing new in the Aquatic Ruin Zone, and the latest one has dragged up several ruins from the ancient underwater city, including a massive stone statue. The Kintobor Computer has noticed this, and Sonic is keen to check it out. With Johnny and Porker on reconnaissance, Amy taking care of personal business and Tails on another adventure in the Nameless Zone, Sonic takes a Star Post to the Aquatic Ruin alone, and soon comes face to face with the statue (which he thinks is a giant Badnik) and a group of Whisp Badniks. After freeing the Badniks' organic batteries and suggesting that they hide before he takes them home, Sonic is attacked by arrows and falls into the water. Before he can return to the surface, the hedgehog is trapped under falling pillars and unable to reach the nearby air bubbles. Suddenly, the statue comes to life and frees Sonic. He thinks it plans to take him to Dr Robotnik, but the statue knows nothing of Robotnik. It introduces itself as a Sentinel, built by the ancient ones to guard the city and having lain dormant for over 2000 years. As the city sank, its masters left Mobius without it, the Sentinel trapped in a tremor. With the city deserted, the Sentinel decides it has no purpose and falls apart there and then, Sonic's pleas for it to stay and help against Robotnik going unnoticed, leaving the annoyed hedgehog to merely stare on the bubbles on the lake's surface.
The Sentinel was reprinted in Issue 133, marking the beginning of all previous strips being reprinted for the benefit of new readers.