Ogrons were strong, ape-like humanoids of limited intelligence, typically used by other species as mercenaries. They were most often employed by the Daleks.
Ogrons had a mix of Human and ape traits. It was believed that this mixture of traits was due to climatic changes on their home planet. They were around 7 feet tall, with bowed legs, long arms and barrelled chests. Their faces were flat, with a powerful jaw and small eyes. Ogrons had immense strength, far greater than a Human. Their nervous systems were highly resistant to shock and were protected by muscles, meaning that they could survive multiple bullets. Their only weak spot was the top of their head.
Ogrons were relatively unintelligent, spoke in simple sentences and had obedient, stoic personalities. They had some skills, such as piloting spaceships, but this was believed to be advanced mimicry. Despite this, Ogron speech used subsonic frequencies, which meant that were more intelligent than they might have appeared.
The Ogrons lived in scattered communities on a planet on the outer fringes of the Mutter's Spiral, far from the central space-ways. The dominant lifeform on their home planet was a monster which preyed upon the Ogrons, yet they prayed to it with reverence. They would regularly sacrifice their criminals to the monster, after weakening them by starvation. They would leave gifts to its image, painted on the walls of their caves.
This dedication to other parties' goals largely prevented the study of the Ogron culture itself. They were mostly known for their desire to work unquestioningly for several different parties. By far, their most common employers were the Daleks. However, they also worked for the Master and the Remote.
In the 22nd century, the Daleks used the Ogrons as enforcers and soldiers during their invasion of Earth.
In 2540, the Master, working for the Daleks, used Ogrons to attack Draconian and Earth ships, using a device to make them look like the opposite side. They destroyed several ships this way, until they attacked a ship that the Doctor and Jo Grant were on. This led to a series of events leading to the the Master, the Doctor and Jo being captured by the Draconians. When the Ogrons attempted to save the Master, they were able to capture Jo, but accidentally left a corpse behind, allowing the Draconians to see the truth. With this, the Draconians joined forces with Earth and the Doctor and followed the Ogrons to their planet. The Master set a trap for them, leading to their capture. Using the stolen device, the Doctor convinces the Ogrons that he is a Dalek, allowing them to escape. Both Earth and Draconia planned to send forces to stop the Ogrons.
At some point in the late 26th century, several Ogrons were modified to be given advanced intelligence. Most died in the process, except for Garshak. Garshak worked as a policeman on Megerra, and later became a private detective.
Over time, their defeats by the Doctor proved devastating to their planetary economy. Because they depended upon their fearsome reputation to secure contracts with other species, the fact that they were defeated by an older, white-haired humanoid handed them a public relations nightmare. After their employment with the Master, they found it increasingly difficult to convince other species to hire them. Soon, they began losing more and more work to the Judoon, who eclipsed them as the universe's best hired guns. When the Tenth Doctor discovered the unintentional consequences his younger self's actions, he pledged to try to redress the situation. He seemed to have made good on this promise by getting the Ogron Ambassador Brarshak safely to a round of diplomatic negotiations with the Draconians and Sontarans on the planet Luna IV.