The Dr Who Ood are a fascinating alien race. Over the two episodes in which they have featured we have learned a lot about their characteristics and their history.
The physiology of the Dr Who Ood tells us a lot about them. The Ood are humanoid. They all dress alike and there are no obvious male and female differences. The lower part of the Oods face is covered in tendrils, with no visible mouth. The Ood communicate telepathically so their mouths were not a central part of their facial anatomy. All the Dr Who Ood carry something in their hand. When the Ood are enslaved by the humans the humans have fitted a translator device. When the humans did this, they removed the Oods external brain. This brain contained all the Oods personal information and their identity. Without their external brain the Ood were the perfect slave race as they became all alike without individuality.
The Dr Who Ood are clearly a peaceful alien nation. We know this for several reasons, firstly their clothing is not the clothing of soldiers. But most obviously they have evolved in such a way that their communication is superior, but they have visible physical vulnerability which a fighting nation would not. They carry an external brain, this means that they only have one hand free for physical actions, and they have some of their most important information vulnerable to attack, they also have unprotected tendrils on their face.
We learn that the Ood come from a planet called the Ood Sphere, which is close to the Sense Sphere planet. The Sense Sphere planet is inhabited by the Sensorites who we are told are similar to the Ood. The Doctor could not save the enslaved Ood in the episode The Impossible Planet, but in the second encounter with the Ood we discover that there is a hive mind. This hive mind has been captured for over two hundred years, and has changed and evolved to control the Ood in such a way to instigate its release. To achieve the desired end the hive mind had to turn some Ood feral and vengeful. This is another sign of the Ood peaceful mentality, the hive mind was prepared to wait as long as necessary to get back to freedom, there was no immediate fight, the Ood were not called to arms and sent into to fight for the hive mind, it was a long and slow process which the hive mind knew would ultimately work.
By the end of the second appearance of the Dr Who Ood we are all fairly attached to these helpful and accepting creatures. The Dr and Rose help to free the hive mind and to return the Ood to their home, for this the Ood will always in indebted to the Doctor. This clever story line means that the Doctor has an ally who will probably be there to help him at some time in the future. If the Ood are prepared to wait two hundred years for freedom they will probably remember a friend for a long time.