The Uvodni were tall, aggressive humanoids, with insect-like faces. They had brown or greenish skin and large eyes with thin, horizontal pupils. They were stronger than humans, as Uvlavad Kudlak was easily able to lift up Mark Grantham. (TV: Warriors of Kudlak)
The Uvodni utilised powerful teleporters to transport new children warriors onto their ship. These teleports were charged with a process that usually resulted in freak rainfall, similar to an H2O scoop. They owned a variety of weapons. Uvodni like Uvlavad Kudlak and Mark Grantham carried laser pistols, while their Slab warriors were armed with far more available blaster weapons which fired a yellow target seeking laser burst.
During his expedition on Earth, Uvlavad Kudlak used a warship which orbited the Earth. This ship was fitted with crates to hold prisoners, teleport links with Earth and shuttle crafts to be used in emergencies. The ships were patrolled by Kudlak's soldiers, while the Mistress was situated at the bridge of the ship. (TV: Warriors of Kudlak)
In 102, the Uvodni were among the races who joined the Alliance. A representative came to Stonehenge and witnessed the imprisonment of the Eleventh Doctor in the Pandorica in order to save the universe. (TV: The Pandorica Opens) When the plan failed, they were erased from the universe along with almost every other race in the galaxy. However, the Doctor managed to prevent this using the Pandorica, and they were restored to their proper point in time and space. (TV: The Big Bang)
Around the 21st century, the Uvodni were at war with the Malakh race in the Horsehead Nebula in a conflict known as the Ghost Wars. After losing many soldiers, they discovered Earth and the human race, and used their children as soldiers in the far-off battlefields. General Uvlavad Kudlak was in charge of this operation, and he duped a human named Mark Grantham to help him. They only kidnapped the children that had won Level 2 in the futuristic war game Combat 3000.
At some point in the 21st century, the Uvodni and the Malakh signed a peace treaty. Mistress, the computer controlling Uvlavad's ship, was not programmed to understand peace and refused to tell Uvlavad of the end of the war, meaning he continued to kidnap children. Eventually, Sarah Jane Smith caught wind of his activities and was able to stop him by informing him of the end of the war. Uvlavad destroyed Mistress and, after having an offer to give his life in atonement of his actions refused, agreed to try to find all the children he had kidnapped. (TV: Warriors of Kudlak)
In 2009 one Uvodni was captured by the Krulius and stored in a data-pod. The Krulius later used his digital bio-converter to upload the Uvodni's bio data onto the internet. There it was found by Mr Smith, Rani Chandra and Clyde Langer who sent the Uvodni back to its original place. (COMIC: Monster Hunt) The Krulius later told Rani Chandra that he had managed to take clone cell samples of his former captured aliens with him, which allowed him to grow perfect copies of these aliens. (COMIC: Return of the Krulius)
In late 2010, an Uvodni, called General Kudlak, took part at the army of alien slaves led by the Krulius to attack Sarah Jane's house. When Clyde defeated several of the aliens, the Uvodni regrouped with the army and the Krulius ordered them to retreat. Sarah Jane thought that the aliens were under some kind of hypnothic influence. (COMIC: Defending Bannerman Road)