Jata was an Osumaran who was a companion of the Twelfth Doctor. The Doctor rescued Jata from being stranded on Earth and they had several adventures together on the voyage back to Jata's homeplanet Osumare.
Stuck on Earth
In 1899, Jata crashed onto Earth in Wyoming and was found by Clint Currie. Deciding to "make the best of [the] barbaric world", Jata helped Currie commit crimes. Jata became the mastermind behind a number of big-time hold-ups and robberies. Because the black star on Jata's forehead was unique on Earth, Jata was put on wanted posters that identified Jata as Currie's horse.
Three months after Jata came to Earth, the Twelfth Doctor found his crashed spaceship. He came to a town that Currie's gang were committing a robbery in. While Currie's gang were robbing a train, the Doctor came to the tree which Jata was tied to. Jata willingly came with the Doctor and the Doctor left a regular white horse with a black star painted on its forehead in Jata's place. Without the Osumaran to guide him, Currie was caught and arrested by the town's sheriff.
Travelling with the Doctor
After Jata expressed an interest in educational systems, the Doctor took him to a school in early 21st century England. After they discovered that all of the students had become violent mindless zombies, Jata allowed the Doctor to ride him to safety. Jata and the Doctor realised that Ralph, the only student to escape the "zombie" students, was actually a Mkali who was responsible for the goings-on at the school. The Doctor phoned Ralph's mum and got her to fix all the damage Ralph had done. Jata let the back-to-normal students pet and groom him. (COMIC: Fear Buds)
Coming to Dacea for its interesting plantlife, Jata and the Doctor accidentally became guests at the royal marriage of Syllience and Arcanbryte. When Bowack's pirates seemingly kidnapped Arcanbryte, Jata and the Doctor chased after them. Jata revealed his ability of flight to the Doctor when Bowack's sled took to the skies. Jata got onto Bowack's zeppelin the ventilation shafts, where he and the Doctor learned that Arcanbryte actually loved Bowack. Conveniently, King Syllience was actually in love with Dorella. The Doctor and Jata attended the double wedding of Syllience and Dorella and Arcanbryte and Bowack. (COMIC: Royal Wedding)
On Bode 215, Jata and the Doctor encountered a colonel who was planning on eradicating the local giant worms with drones. The Doctor met up with the worms and destroyed the drones pretty much by himself. (COMIC: Night of the Worms)
Investigating reports of irregular behaviour among schoolchildren on Earth in the 2010s, Jata and the Doctor witnessed an alien harvesting the minds of several students to form part of a Super Mind. Jata and the Doctor used the TARDIS to go to the alien's space station, where they confronted the alien and tricked it into being absorbed into its Super Mind. Once all the students were rescued from the Super Mind, Jata helped calm them by giving free "pony rides". (COMIC: Killer App)
Jata considered humans to be inferior; calling Earth a barbaric planet. (COMIC: From the Horse's Mouth) When the Doctor introduced him to the human colony Bode 215, Jata's first question was "have [the humans] made a mess of it yet?". (COMIC: Night of the Worms)
Behind the scenes
All of the stories to feature Jata were written by Andrew Cartmel. During Jata's time as a regular companion in the Doctor Who Adventures comic, the magazine saw major changes. Because the magazine became published bi-monthly, stories written for late 2016 were pushed back to 2017. Jata became the first companion original to DWA to be in a comic published while another companion (Bill Potts) was with the Doctor on television.