The Judoon are huge rhinos who are actually policemen.
The Judoon work at the Shadow Ploclamation and for the Shadow Arcitect. The Doctor first encountered them on the Moon when he was inside a hospital. The hospital was teleported to the Moon as there was a criminal alien on board called a Plasmavore. The Plasmavore killed the child princess and was being hunted down by the Judoon. There were three Judoon ships which landed on the Moon.The Judoon Captain took off his mask and showed the humans he was actually a rhino. The Judoon carry with them a scanner, a blaster gun and a translator which the captain used on a student who was Oliver Morganson. The Judoon scanned the humans and marked their skin with a black cross. At one point a human attacked a Judoon and the captain blasted him into pieces. The Judoon however found the Doctor and thought he was the alien as he was non-human. The Judoon chased him but then lost him. The Doctor found the Plasmavore but was caught by one of her Slabs. Then she attempted to suck him dry until Martha entered with the Judoon. Florence the Plasmavore had already been scanned as a human by drinking Mr Stoker's blood. Martha then used the scanner on her and she registered as non-human as she drank the Doctor's blood. She activated the controls but when her Slab tried to attack the Judoon he was blasted. Then she wanted to kill the humans and the Judoon but they blasted her too. Then the Judoon left the Moon and sent the hospital back to London.
The Doctor did take Donna to the Shadow Ploclamation and he told the Judoon to take him to the Shadow Arcitect. The Judoon told Donna that the planets she mentioned were cold case as they went missing thousands or hundreds of years ago. They were Adipose 3 and Pyrovillia. Then when the Doctor figured it out the Shadow Arcitect and the Judoon tried to stop him from leaving but he just left anyway.A Judoon Captain crash landed on Earth as he crossed the solar system in 35 minutes. He had a prisoner on his ship called Androvax who was destroyer of worlds. When Sarah Jane and her gang found the Judoon he was hit over the head. He said he was Captain Tybo. Luke and Rani distracted Typho but when he found out he destroyed their mobliles. When they found Clyde, Tybo woke him up. However after this Tybo threatened the police and comandiered their vehicle. He then drove the police car and scared a teenager. He drove them to Sarah Jane's house and then found out that Mr Smith was a bomb. Then Luke managed to save them all they left and headed for the science industries. Androvax needed to micro creatures to build his spaceship. Then when Tybo, Clyde, Luke and Rani arrived Tybo made them pay for parking! Then when they entered Tybo was going to ask Rani's parents for information but he was stopped. Then his Judoon troopers had landed and he was tricked by Clyde into a room where his equipment was useless. Tybo then chased Clyde and Rani onto Androvax's spaceship and arrested him. Tybo grounded Luke, Clyde and Rani so that they could only stay on Earth. Tybo then left them with Andorovax.
There were three Judoon at the Pandorica as they were part of the Pandorica Alliance. They trapped the Doctor inside the Pandorica because he caused the cracks in time. The other aliens of the Alliance were Daleks, Cybermen, Silurians, Sontarans and many more.
There were also two Judoon on Demon's Run but this time they were helping the Doctor!
The Judoon have appeared in:
Series 3: Smith and Jones
Series 4: The Stolen Earth
The Sarah Jane Adventures Series 3: Prisoner of the Judoon
Series 5: The Pandorica Opens
Series 6: A Good Man Goes to War