Omega Sentinel is a Decepticon from the Dreamwave portion of the Generation 1 continuity family.

Omega Sentinel is immense—immensely strong, immensely logical, and immensely powerful. Once sent to Earth to locate the missing Omega Supreme, the Omega Sentinel was found instead by the Decepticons, and lent his awesome firepower to their cause. Megatron described him as a cross between Shockwave's mind and Devastator's power. Although not as ambitious as Shockwave, the Omega Sentinel is also loyal only to his sense of logic, and will switch allegiances at a moment's notice if his analysis dictates it. The Omega Sentinel's deep devotion to logic makes dealing with the highly emotional human populace of Earth difficult at times. Fortunately, as a Decepticon, the Sentinel can simply destroy anything that strikes him as illogical and be done with it.

Fiction

Dreamwave Generation One continuity

The Transformers Trilogy

The Omega Sentinel was apparently sent out into space some time ago, searching for Omega Supreme. He eventually found the planet Earth, but was taken in by the Decepticons before he could locate Omega Supreme. Through reprogramming, Megatron succeeded in bringing the Omega Sentinel in line with the Decepticon cause. He planned on using the giant as a secret weapon against the Autobots at a later date, but those plans were dropped once Megatron was kidnapped by the Keepers and Starscream assumed command of the Decepticons. Starscream activated the Omega Sentinel and brought him to the new Decepticon capitol, Las Vegas. Omega Sentinel was present in Vegas when Megatron returned from space with the Keepers in tow. Although he was too badly injured to retake command of the Decepticons by force, Megatron nevertheless refused to serve under Starscream, and several Decepticons made the same choice, including Sentinel, who did not find Starscream logical. The loss of the Omega Sentinel was one of the most crushing blows to Starscream's command.

The renegade Decepticons made an alliance with the Autobots against the Keepers, and returned to Las Vegas to annihilate the aliens after they executed Starscream and bestowed his corpse on one of their own as a host body. The Omega Sentinel planned to personally obliterate the Keeper-Starscream in battle, but he and Devastator were held back from the final conflict by an energy field generated by the Keepers. Worse still, this meant they were too far away from Optimus Prime when he used the power of the Matrix to defend all the other Autobots and Decepticons present from a nuclear blast, launched at the Keepers by the US military. Having absorbed the brunt of the radioactive fire, Omega Sentinel was rendered totally inoperative and unsalvagable. Annihilation

Or was he? The Sentinel was actually quite salvagable, and was quickly restored to full functioning. Megatron kept the Omega Sentinel's restoration a secret, in order to make him a secret weapon against the Autobots once again. This proved to be extremely fruitful almost immediately: due to a debt of honor, Megatron was able to convince Optimus Prime to hand over the Matrix to the Decepticons. Prime realized he was drastically inhibiting the Autobots' power, but little did he dream that Megatron would ever be able to actually tap the Matrix's power for evil purposes. In fact, the non-Decepticon origins of Omega Sentinel's circuitry allowed him to utilize the Matrix somewhat. He had it placed inside his chest panel and began drawing from its limitless power. His first act as a Matrix-enhanced being was to demolish the White House and retrieve the President of the United States for Megatron's amusement.

Using the Matrix improperly has its consequences, though. Despite the massive damage the Omega Sentinel caused in Washington D.C., not a single life was lost. And, when Megatron commanded the Sentinel to destroy the Keepers' puppets Bluestreak and Starscream, he found that he could not. Realizing that the Matrix was affecting the Omega Sentinel's systems, Megatron made his soldier remove the object as quickly as possible. Once the Sentinel threw away the Matrix, however, it was recovered by the Keepers' human agent Franklin Townsend, leaving both the Autobots and Decepticons without its power.

The influence on Omega Sentinel's programming did not stop there, however. Even without the Matrix inside him, Omega Sentinel continued to prove unwilling to injure living beings. In a battle with the American military in the Nevada desert, he used a sleep-inducing ray on the soldiers instead of harming them. Ultimately, the Omega Sentinel's true command protocols as a Guardian robot reasserted themselves, and he turned against Megatron during the final battle to prevent the Keepers from gaining a foothold on Earth. The Omega Sentinel thrust himself through the gateway the Keepers had constructed for their arrival and crushed the crystal key that was the source of their power. The resulting discharge destroyed the Omega Sentinel, the Keepers, and the Void dimension they resided in. Fusion

Notes

• The Omega Sentinel's appearance is unknown. Presumably, he looks like the typical "Guardian Robot" design used for Omega Supreme and other generic Guardians. He is first described as black and gold (Annihilation p. 64), but later as blue and red (Fusion p. 12), the latter being the traditional colors of the Guardians.
• Judging from his initial description, the Omega Sentinel was ostensibly originally supposed to be Omega Supreme himself, with his role replaced by the Omega Sentinel so as to not interfere with plans for Omega Supreme proper in the concurrently-published Dreamwave comics.